Dinosaur Mysteries digs into the secretive side of the “terrible lizards” and all the questions that keep paleontologists up at night.

YOU NEVER KNOW how small you are until you’re next to a big ol’ dinosaur. Find the right lighting in the museum hall and you can literally stand in the shadow of the skeletons of Apatosaurus, Patagotitan, Brachiosaurus, and other reptiles that grew far larger than any other terrestrial creature in the past 66 million years. But even after nearly two centuries of research, we have only the haziest notions of why some dinosaurs were larger than any terrestrial mammal to date.

While a number of dinosaurs fell in the supersized category—Tyrannosaurus rex weighed more than a mature male African elephant—the sauropods were the all-time titleholders. They had small heads with simple teeth, impressively long necks, hefty bodies, and tapering tails. So many sauropod species reached more than 100 feet in length, paleontologists still aren’t sure which one stretched the farthest. While the largest land mammals, like the hornless rhino Paraceratherium and the biggest fossil elephants, got to be about 18 tons, sauropods evolved to have more mass at least 36 times during their evolutionary history—an ongoing reprisal of gargantuan herbivores through the Jurassic and Cretaceous.

The stunning heft of these creatures has often led us to wonder why they got to be so much bigger than any terrestrial creature before or since. But in the realm of paleontology, “why” questions are extremely difficult to answer. Queries starting with “why” are matters of history, and in this case, the history plays out dozens of times on multiple continents over the course of more than 130 million years. Though we see the end effect, we can’t quite make out the causes.

Dinosaurs have a habit of digging their claws into our imaginations, however, so researchers have kept on, turning up a few clues in the past two decades about the surfeit of superlative sauropods. While higher oxygen levels have been linked to bigger body sizes in a few ancient insects, the atmosphere in the heyday of the dinosaurs was about the same as today’s. What’s more, the Earth’s gravitational force was just as strong in the Mesozoic era as in the modern era. So we know that the impressive size of Argentinosaurus and other top sauropods was not a matter of an abiotic factor like increased oxygen in the atmosphere or lower gravity. Our explanation lies elsewhere.

Paleontologists are getting closer to the truth by looking at the dinosaurs themselves. For example, experts have identified a suite of characteristics that set sauropods apart from the mastodons and giant rhinos of the Cenozoic. Eggs have a great deal to do with it.

The largest mammals of all time were placentals, gestating their offspring on the inside so they could come out more developed. This reproductive strategy comes with some constraints. To reach even larger adult sizes, females of each species would need to carry their babies in the womb for longer. African elephants, for example, already gestate for about two years—during which much can go wrong. But sauropods, like all nonavian dinosaurs, laid multiple eggs at a time, bypassing the reproductive constraints of live birth and flooding their ecosystems with tons of babies that had the potential to grow huge (even if most ended up as snacks for the carnivores of the time). The different reproductive strategies gave dinosaurs some advantages over mammals.

Camarasaurus and other sauropods also got some assistance from their anatomical peculiarities. Sauropods had complex air-sac systems in their respiratory tracts that created air pockets within and around their bones. These nifty features kept their skeletons light without sacrificing strength, and also made extracting oxygen from the air and shedding excess body heat more efficient. The distinctive dinosaurs could grow long necks too, because they didn’t have heavy heads full of massive, grinding teeth like large herbivorous mammals over the past 66 million years. Instead, sauropods had small, light noggins full of spoon- or pencil-shaped teeth that were mostly just capable of cropping vegetation to be broken down and fermented through their gastrointestinal tracts. In other words, their guts did the work, not their teeth. Studies of ginkgoes, horsetails, and other common Mesozoic plants indicate that the ancient vegetation was more calorie-rich than previously supposed, so the abundance of green food likely fueled the reptilian giants’ unprecedented growth.

But these facts only show us what allowed sauropods to become big. The dinosaurs didn’t have to drift in that direction. In fact, some were relatively small: The island-dwelling species Magyarosaurus was about the size of a large cow. Sauropods could have thrived at smaller sizes, but they instead kept spinning off lineages of giants. We know something about what made living large possible, but what we still don’t know is what evolutionary pressures drove sauropods to evolve enormous bodies.

Predators certainly played their part. All sauropods were born small—even the largest species hatched from eggs about the size of a soccer ball. They were vulnerable to various Jurassic and Cretaceous carnivores, but growing up quickly was one way to stave off those hungry jaws. Hunting megafauna can be dangerous and even deadly, as we see with lions, wolves, and even humans today, and so sauropods may have plumped up to be less appealing to the likes of Allosaurus and T. rex.

But if carnivorous appetites were the main driver of sauropod size, we’d see a more uniform and extended “arms race” between the dinosaurs over time, resulting in gradually larger predators and prey. The fossil record instead shows that sauropods scaled up in different times and places, likely for an array of reasons ranging from local grub to what mating sauropods found sexy in each other. The repeated evolution of gigantic dinosaurs hints that there were many pathways to the sauropods’ impressive stature, not just one. Biology was as complicated back then as it is now, and we’ll never get the full story without experiencing 100-foot-long reptiles ourselves.

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Scavenging has been maligned as a food gathering strategy and is generally associated with animals like vultures and hyenas. Millions of years ago, carnivorous dinosaurs may have evolved this technique of taking meat from dead carcasses too. The findings are described in a study published November 1 in the open-access journal PLOS ONE.

[Related: Dinosaur cannibalism was real, and Colorado paleontologists have the bones to prove it.]

Carnivorous dinosaurs like the cannibalistic Allosaurus were surrounded by both living and dead prey. The bodies of large sauropod dinosaurs, some of whom could weigh more than 500,000 pounds, could have provided an important food source for carnivores.

In this study, a team of researchers from Portland State University created a simplified computer simulation of a dinosaur ecosystem from the Jurassic age. They used the animals that have been found in the 163.5 to 145 million year-old Morrison Formation in the western United States as the basis. This enormous fossil formation was once home to a wide variety of plants and dinosaurs.

The model included large carnivores common to the area like Allosaurus, large sauropods and their carcasses, and a large group of living and huntable Stegosaurus’. The carnivores were assigned traits that would improve their hunting abilities with the energy from living meat sources or their scavenging abilities with the sustenance from the carcasses. The model then measured the evolutionary fitness of the simulated predators. 

The model found that when there were a large amount of sauropod carcasses around, scavenging was more profitable than hunting for the Allosaurus. Meat eaters in these kinds of ecosystems may have evolved specialized traits to help them detect and exploit these large carcasses.

“Our evolutionary model demonstrates that large theropods such as Allosaurus could have evolved to subsist on sauropod carrion as their primary resource,” the authors wrote in a statement. “Even when huntable prey was available to them, selection pressure favored the scavengers, while the predators suffered from lower fitness.”

[Related: This 30-pound eagle would take down 400-pound prey and dig through their organs.]

This model represents only a simplified depiction of a complex ecosystem, so more variables like additional dinosaur species may alter the results. While theoretical, using models like this one can help scientists better understand how the availability of meat from carcasses can influence how predators evolve. A September 2023 modeling study found that even early humans living in southern Europe roughly 1.2 to 0.8 million years ago were scavengers. They may have competed in groups of five or more to fight off extinct giant hyenas for the carcasses of animals that had been abandoned by larger predators like saber-toothed cats.

“We think allosaurs probably waited until a bunch of sauropods died in the dry season, feasted on their carcasses, stored the fat in their tails, then waited until the next season to repeat the process,” the authors wrote. “This makes sense logically too, because a single sauropod carcass had enough calories to sustain 25 or so allosaurs for weeks or even months, and sauropods were often the most abundant dinosaurs in the environment.”

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With its 19 feet-long torpedo-shaped body and long teeth the newly-described Lorrainosaurus was a fearsome mega predator. The fossilized remains of a 170-million-year-old marine reptile is the oldest-known pliosaur and dates back to the Jurassic era. The discovery is described in a study published October 16 in the journal Scientific Reports.

[Related: Millions of years ago, marine reptiles may have used Nevada as a birthing ground.]

Pliosaurs were members of a group of ocean-dwelling reptiles that are closely related to the more famous long-necked plesiosaurs. Unlike their cousins, these pliosaurs had short necks and massive skulls. From snout to tail, it was likely about 19 feet long and very little is known about the plesiosaurs from this time.

“Famous examples, such as Pliosaurus and Kronosaurus–some of the world’s largest pliosaurs–were absolutely enormous with body-lengths exceeding 10m [32 feet]. They were ecological equivalents of today’s killer whales and would have eaten a range of prey including squid-like cephalopods, large fish and other marine reptiles. These have all been found as preserved gut contents,” study co-author and Uppsala University paleontologist Benjamin Kear said in a statement.

Pliosaurs first emerged over 200 million years ago and remained relatively small players in marine ecosystems. Following a landmark restructuring of the marine predator ecosystem in the early to middle Jurassic era (about 175 to 171 million years ago) they reached apex predator status.

“This event profoundly affected many marine reptile groups and brought mega predatory pliosaurids to dominance over ‘fish-like’ ichthyosaurs, ancient marine crocodile relatives, and other large-bodied predatory plesiosaurs,” study co-author and paleobiologist at the Institute of Paleobiology of the Polish Academy of Sciences Daniel Madzia said in a statement.

The fossils in this study were originally found in 1983 in northeastern France, but were recently analyzed by an international team of paleontologists who identified this new pliosaur genus called Lorrainosaurus. The teeth and bones represent what was once a complete skeleton that decomposed and was spread along the ancient seafloor by scavengers and ocean currents. 

[Related: The planet’s first filter feeder could be this extinct marine reptile.]

“Lorrainosaurus was one of the first truly huge pliosaurs. It gave rise to a dynasty of marine reptile mega-predators that ruled the oceans for around 80 million years,” Sven Sachs, a study co-author and paleontologist from the Naturkunde-Museum Bielefeld in Germany, said in a statement.

Other than a short report published in 1994, these fossils remained obscure until the team reevaluated the specimens. Finding Lorrainosaurus’ remains indicates that the reign of gigantic mega-predatory pliosaurs likely began earlier than paleontologists previously thought. These giants were also locally responsive to the major ecological changes in the marine environments that covered present day Europe during the early Middle Jurassic.

“Lorrainosaurus is thus a critical addition to our knowledge of ancient marine reptiles from a time in the Age of Dinosaurs that has as yet been incompletely understood,” said Kear.

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Meet Garumbatitan morellensis, a new species of large sauropod dinosaur. The Giganotosaurus relative called the present-day Iberian Peninsula home about 122 million years ago. The remains of this titan were discovered in Morella, Spain, and this discovery could help fill in some major evolutionary gaps. The findings were described in a study published September 28 in the journal Zoological Journal of the Linnean Society.

[Related: Cushy feet supported sauropods’ gigantic bodies.]

G. morellensis belongs to the sauropod group of dinosaurs, which includes some well-known favorites like Diplodocus and Brachiosaurus. Sauropods were four-legged Early Jurassic and Cretaceous Era dinos known for their long necks that could reach up to 49 feet long in some species and lengthy tails. G. morellensis is also a member of a subgroup of sauropods known as titanosaurs. These giants were the largest of an already big group and titanosaurs survived right up until the asteroid that wiped out the dinosaurs struck about 66 million years ago.

This new dinosaur’s remains were found and excavated in the Sant Antoni de la Vespa fossil-site in 2005 and 2008. This fossil deposit is home to one of the largest concentrations of sauropod dinosaur remains that date back to the Lower Cretaceous period in Europe (about 145 million to 66 million years ago). Scientists found the remains of a giant unidentified sauropod in Portugal in 2022 that could be Europe’s oldest known dinosaur fossil at 150 million-years-old. 

The team of paleontologists from Portugal and Spain found the remains of three G. morellensis individuals and one other sauropod. Their lucky find included a rare set of footprints. They also uncovered giant vertebrae, leg bones, and two near-complete sets of foot bones. 

“One of the individuals we found stands out for its large size, with vertebrae more than one meter wide [3.2 feet], and a femur that could reach two meters [6.5 feet] in length. We found two almost complete and articulated feet in this deposit, which is particularly rare in the geological record,” study co-author and University of Lisbon paleontologist Pedro Mocho said in a statement. 

G. morellensis was probably close to an average-size titanosaur and could have been near 94 feet long. Its leg shape and foot bones suggest that it was one of the more primitive sauropods from a subgroup called Somphospondyli, according to the authors. Somphospondylan fossils have been found on every present-day continent, but paleontologists are not sure where they originated. This discovery of such an early specimen in Spain points to Europe as a possible origin point for this subgroup, but more evidence is needed.  

[Related: Europe’s largest dinosaur skeleton may have been hiding in a Portuguese backyard.]

This discovery also highlights how complex the evolutionary history of sauropods in the Iberian Peninsula and the rest of Europe is. Species related to these lineages have been found in Asia, North America, and possibly Africa. This points to a potentially long period of dinosaur dispersal within continents and this fossil deposit might fill in some major gaps of evolutionary history. 

“The future restoration of all fossil materials found in this deposit will add important information to understand the initial evolution of this group of sauropods that dominated dinosaur faunas during the last million years of the Mesozoic era,” study co-author and Universidad Nacional de Educación a Distancia in Madrid paleontologist Francisco Ortega said in a statement.

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We all know the line: For more than 150 million years, dinosaurs ruled the Earth. We imagine bloodthirsty tyrannosaurs ripping into screaming duckbills, gigantic sauropods shaking the ground with their thunderous footfalls, and spiky stegosaurs swinging their tails in a reign of reptiles so magnificent, it took the unexpected strike of a six-mile-wide asteroid to end it. The ensuing catastrophe handed the world to the mammals, our ancestors and relatives, so that 66 million years later we can claim to have taken over what the terrible lizards left behind. It’s a dramatic retelling of history that is fundamentally wrong on several counts. Let’s talk about some of the worst rumors and what really happened in the so-called “Age of Dinosaurs.”

Myth: Dinosaurs dominated the planet from their origin.

Fact: Dinosaurs started as cute pipsqueaks.

The oldest dinosaurs we know about are around 235 million years old, from the middle part of the Triassic Period. Those reptiles didn’t rule anything. From recent finds in Africa, South America, and Europe, we know that they were no bigger than a medium-sized dog and were lanky, omnivorous creatures that munched on leaves and beetles. Ancient relatives of crocodiles, by contrast, were much more abundant and diverse. Among the Triassic crocodile cousins were sharp-toothed carnivores that chased after large prey on two legs, “armadillodiles” covered in bony scutes and spikes, and beaked, almost ostrich-like creatures that gobbled up ferns.

Even as early dinosaurs began to evolve into the main lineages that would thrive during the rest of the Mesozoic, most were small and rare compared to the crocodile cousins. The first big herbivorous dinosaurs, which reached about 27 feet in length, didn’t evolve until near the end of the Triassic, around 214 million years ago. But everything changed at the end of the Triassic. Intense volcanic eruptions in the middle of Pangaea altered the global climate; the gases released into the air caused the world to swing between hot and cold phases. By then, dinosaurs had evolved warm-blooded metabolisms and insulating coats of feathers, leaving them relatively unfazed through the crisis, while many other forms of reptiles perished. Had this mass extinction not transpired, we might have had more of an “Age of Crocodiles”—or at least a very different history with a much broader cast of reptilian characters. The only reason the so-called Age of Dinosaurs came to be is because they got lucky in the face of global extinction.

Myth: Dinosaurs spanned the entire planet.

Fact: Dinosaurs never evolved to live at sea.

Of course, these ecosystems were built on a foundation of plankton. Without disc-shaped algae called coccoliths, the rest of the charismatic swimmers of the Triassic, Jurassic, and Cretaceous wouldn’t have thrived. It’s the abundant, small forms of life that let charismatic creatures like marine reptiles prosper—a further reminder that the animals that impress us on land or sea wouldn’t exist without various tiny organisms that set the foundations of food webs. What we might see as dominance, in any ecosystem, is really a consequence of many relationships and interactions that often go unnoticed.

Myth: Dinosaurs suppressed the evolution of mammals.

Fact: Mammals thrived throughout the Age of Dinosaurs.

The classic example of dinosaur dominance is a twitchy little mammal chasing an insect through the Cretaceous night. Dinosaurs would gobble up any beast that got too big or was foolish enough to wander out in the daylight, the argument went, so mammals evolved to be small and nocturnal until the asteroid allowed our ancestors and relatives to emerge from the shadows. The small size and insect-hunting adaptations of some Mesozoic mammals were taken as indicators that mammals were constrained by the success of the dinosaurs, preventing them from becoming larger or opening new niches.

In the past 20 years, however, paleontologists have rewritten the classic story to show that mammals and their relatives thrived alongside the dinosaurs. Throughout the Mesozoic there were furry beasts that swam, dug, glided between the trees, and even ate little dinosaurs. Ancient equivalents of squirrels, raccoons, otters, beavers, sugar gliders, aardvarks, and more evolved through the Jurassic and Cretaceous, including early primates that scampered through the trees over the heads of T. rexes. While it’s true that all the Mesozoic mammals we presently know of were small—the largest was about the size of an American badger— researchers have realized that the way our ancient ancestors interacted with each other was much more important to shaping their evolution than the dinosaurs were. In fact, even with the dinosaurs gone, most new mammal species stuck to being small. We get so hung up on size that we’ve missed the real story, closer to the ground.

Myth: Dinosaurs dominated the planet for millions of years.

Fact: No single species can dominate a planet.

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Despite having the critical and even miraculous ingredients to sustain life from microscopic viruses up to big blue whales, planet Earth likely has a future that spells some doom for most, if not all, species of mammals—including humans. A study published September 25 in the journal Nature Geosciences made the bold prediction that in about 250 million years, all of Earth’s major land masses will join together as one. When they do, it could make our planet one extremely hot and almost completely uninhabitable for mammals.

[Related: Mixing volcanic ash with meteorites may have jump-started life on Earth.]

“Widespread temperatures of between 40 to 50 degrees Celsius [104 to 122 degrees Fahrenheit], and even greater daily extremes, compounded by high levels of humidity would ultimately seal our fate,” study co-author and University of Bristol paleoclimatologist Alexander Farnsworth said in a statement. “Humans—along with many other species—would expire due to their inability to shed this heat through sweat, cooling their bodies.”

The models in this study predict that CO₂ levels would rise to between 410 parts per million and 816 parts per million in a few million years This is roughly the same as today’s level, which is already pushing the planet into dangerously hot water, or up to twice as high.

“They do explain quite nicely that it’s a combination of both those factors, kind of a double whammy situation,” geophysicist Ross Mitchell of the Chinese Academy of Sciences, who was not involved in the study, told Science magazine. “If there’s any disagreement I have with this paper, it’s that they’re more right than they thought they were.”

This prediction aligns well with Earth’s past periods of mass extinction and the volatile history of our planet. Here are some other times that mammalian and human life on Earth was almost completely wiped out.

The Pleistocene Ancestral Bottleneck

About 800,000 to 900,000 years ago, the population of human ancestors drastically dropped. A study published in August estimates that there were only about 1,280 breeding individuals alive during this transition between the early and middle Pleistocene. About 98.7 percent of the ancestral population was lost at the beginning of this ancestral bottleneck that lasted for roughly 117,000 years.

During this time, modern humans spread outside of the African continents and other early human species like Neanderthals began to go extinct. The Australian continent and the Americas also saw humans for the first time and the climate was generally cold. 

Some of the potential reasons behind this population drop are mostly related to extremes in climate. Temperatures changed, severe droughts persisted, and food sources may have dwindled as animals like mammoths, mastodons, and giant sloths went extinct. According to the study, an estimated 65.85 percent of current genetic diversity may have been lost due to this bottleneck.

[Related: We’re one step closer to identifying the first-ever mammals.]

The Great Dying

About 250 million years ago, massive volcanic eruptions triggered catastrophic climate changes that killed 80 to 90 percent of species on Earth. The Permian-Triassic mass extinction, or the “Great Dying,” paved the way for dinosaurs to dominate Earth, but was even worse than the Cretaceous–Paleogene extinction that wiped out the dinosaurs 66 million years ago.

According to a study published in May, saber-toothed creature called Inostrancevia filled a gap in southern Pangea’s ecosystem, when it was already devoid of top predators. Eventually, Inostrancevia also went extinct about 252 million years ago, as Earth’s species fought to gain a foothold on a changing planet. 

This example of how the past is prologue also bears a warning for our future, since the team says The Great Dying is the historical event that most closely parallels Earth’s current environmental crisis.

“Both involve global warming related to the release of greenhouse gasses, driven by volcanoes in the Permian and human actions currently,” study co-author museum curator and paleontologist Christian Kammerer told PopSci in May. “[They] represent a very rare case of rapid shifts between icehouse and hothouse Earth. So, the turmoil we observe in late Permian ecosystems, with whole sections of the food web being lost, represents a preview for our world if we don’t change things fast.”

The Ultimate Mammalian Survivor

Despite Earth constantly trying to kill us, life finds a way. Some of our very early ancestors potentially even shared a brief moment with Titanosaurs and the iconic Triceratops. These distant mammalian relatives also survived the Earth’s most famous mass extinction event: the Cretaceous-Paleogene (K-Pg) mass extinction that wiped out non-avian dinosaurs on a spring day about 66 million years ago.

[Related: This badger-like mammal may have died while trying to eat a dinosaur.]

A study published in June revealed that a Cretaceous origin for placental mammals, the diverse group that includes humans, dogs, and bats, briefly co-existed with dinosaurs. After an asteroid struck the Earth near Mexico’s Yucatán Peninsula, the devastation in its wake wiped out all of the non-avian dinosaurs and many mammals, such as a Madagascan rodent-looking animal named Vintana sertichi  that weighed up to 20 pounds Scientists have long debated if placental mammals were present with the dinosaurs before the Cretaceous-Paleogene (K-Pg) mass extinction, or if they only evolved after the dinosaurs died out. 

This study used statistical analysis that showed groups that include primates, rabbits and hares (Lagomorpha), and dogs and cats (Carnivora) evolved just before the K-Pg mass extinction and the impact that the modern lines of today’s placental mammals started to take shape after the asteroid hit. As with other mammals, they likely began to diversify once the dinosaurs were out of the picture.

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It sounds hard to believe, but even before dinosaurs were a thing, big, weird, and sometimes scary animals were wandering around the planet. A newly found example of such an odd creature was discovered in a rural part of São Gabriel in southern Brazil—the Pampaphoneus biccai. According to the researchers studying the 265-million-year-old beast, it was likely the toughest, biggest, and blood-thirstiest carnivore that South America had seen at the time. 

“This animal was a gnarly-looking beast, and it must have evoked sheer dread in anything that crossed its path,” Stephanie E. Pierce, a professor at the Museum of Comparative Zoology at Harvard and co-author of a new study describing the creature, said in a statement. “Its discovery is key to providing a glimpse into the community structure of terrestrial ecosystems just prior to the biggest mass extinction of all time. A spectacular find that demonstrates the global importance of Brazil’s fossil record.”

The fossil, found in middle Permian rocks, included a complete skull and some skeletal bones such as ribs and arms. This specimen is only the second of the Pampaphoneus genus to be found in South America, though other similar specimens have been spotted in Russia. Its 15-inch-long  skull is the largest of its kind ever found intact. In its prime, the Pampaphoneus would have weighed around 881 pounds (about the size of a full-grown cow) and reached around nine feet in length—a fearful Permian predator, to say the least. 

[Related: Move over, Stegosaurus, there’s a new armored dino in town.]

The Pampaphoneus belonged to the dinocephalian clade, which in Greek means “terrible head”—a shout out to their thick cranial and skull bones. This large family of animals were the first non-mammalian therapsid to be scientifically described, and they largely died out before the Capitanian mass extinction event that predated the Permian extinction. Therapsids are a group of vertebrate animals that predate mammals and all of their ancestors. 

The Brazilian Pampaphoneus filled the same ecological niche as modern big cats, Felipe Pinheiro of the Paleontology Laboratory at the Federal University of Pampa (UNIPAMPA), said in the release. “It was the largest terrestrial predator we know of from the Permian in South America,” the study co-author added. “The animal had large, sharp canine teeth adapted for capturing prey. Its dentition and cranial architecture suggest that its bite was strong enough to chew bones, much like modern-day hyenas.”

Some of this potential prey has already been identified, such as the tusked Rastodon and the giant amphibian Konzhukovia. But there’s still much to learn about this terrifying therapsid, and its life before the largest extinction event in the history of the planet.

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Dinosaur Mysteries digs into the secretive side of the “terrible lizards” and all the questions that keep paleontologists up at night.

WE STILL LIVE in an age of dinosaurs. Pigeons, penguins, and partridges are all members of the only lineage to survive the asteroid-driven disaster of 66 million years ago. The realization that at least some dinosaurs still flock among us has given a greater depth to paleontology than the field’s founders could have imagined. What we learn about living dinosaurs can help us better understand the species we can touch only as fossils. But even though we can trace the origins of birds from their Velociraptor-like ancestors, there’s one critical part of the story that we don’t fully understand. How on earth did dinosaurs such as Microraptor evolve the ability to fly?

The definition of flight can be a little tricky—it’s not simply about moving through the air. After all, there are marsupials, frogs, snakes, and other animals capable of gliding for impressive distances. Flight is something more specific, requiring the evolution of not only wings but a wing stroke. Watch a raven flap by and you’re watching a dinosaur demonstrate the exact mechanics of keeping itself aloft with one wingbeat after another. The question paleontologists face is how dinosaurs went from terrestrial reptiles scurrying over the ground to feathery, fluttering wonders.

Archaeopteryx lithographica, the earliest recognized bird at about 150 million years old, is of limited help. When the fossil was uncovered in the late 19^th century, the splash of feathers found around the Jurassic dinosaur’s bones were quickly taken as an indication that its kind soared over the forests of prehistoric Bavaria. Over time, however, the genus Archaeopteryx started to look more awkward than aerodynamic. The avian ancestor had asymmetrical flight feathers with a shallow leading edge, a critical adaptation for powered flight—but its skeletal anatomy didn’t look capable of flight the way we see it in living birds. The contradiction led to a longstanding debate over whether Archaeopteryx actively flapped into the air, primarily glided, or perhaps even used a different flight stroke from its modern relatives. Whatever the answer, the solution to the mystery can’t be found in its bones alone. And as further feathery dinosaur species have been uncovered, the caper has only grown more complex.

Since the mid-1990s, paleontologists have uncovered dozens of feathery dinosaurs. Many of them are close relatives of Mesozoic birds or otherwise have adaptations related to flight, including the genus Microraptor, which had long feathers on its legs as well as its long arms. In fact, paleontologists think powered flight evolved at least three times among dinosaurs: once among birds and twice among their close dinosaur relatives such as Rahonavis ostromi. That’s not counting the number of feathery species whose anatomy made them more aerodynamically adept than others, but that still weren’t quite capable of keeping themselves aloft by flapping. Instead of a neat, orderly pattern of flight-related traits among birds and their ancestors, the emerging picture shows a tangled mess.

That changes the entire backstory of flying beasts. Up until recently, feathery dinosaurs were cast as representatives of stages in the evolution of flight. Now paleontologists have to figure out how they evolved flight independently multiple times among both birds and feathery nonavian dinosaurs. The path the ancestors of Archaeopteryx took might not be the same as the path taken by predecessors of Microraptor or Rahonavis.

Experts have tossed plenty of ideas about the origins of flight against the proverbial wall. These are broadly divided into “ground-up” and “trees-down” hypotheses, with most paleontologists favoring explanations that focus on how a ground-dwelling, Velociraptor-esque avian ancestor could evolve the ability to fly. Maybe feathery bird ancestors chased insects, leaping after them and trying to trap them with their arm feathers, which would favor dinosaurs able to stay in the air longer. Or maybe flight started with gliding and dinosaurs climbing trees to swoop through the forest, which would give an advantage to those that could flap their arms to soar just a little farther. The behavior of modern birds has provided some clues too, like the way chukar partridges flap their wings to better stabilize themselves while running up inclines.

Every hypothesis about how airborne dinosaurs evolved focuses on the behavior of animals we can’t observe in life. Experts have to draw out what clues they can from feathers, bones, the universal mechanics of flight, and how birds today manage to get into the air and stay there. While it’s possible to conduct wind-tunnel experiments based on skeletal mechanics and other inferred details to calculate how an Archaeopteryx would have fared while flying, there will always be a difference between what a prehistoric species could have done and how it actually behaved back in the Mesozoic. Evolution is not a tidy progression towards a particular outcome, but a story of constant change full of repeats, dead ends, and diversity.

There can’t be a single solution to the puzzle of how dinosaurs evolved to fly because scientists have more than one case to consider. Whether it consists of birds or nonavian dinosaurs, the history of each lineage has to be studied on its own terms. More than that, what seemed like a basic question about the first flying dinosaurs only creates more questions about what led different dinosaurs in different places and times, many miles and millions of years apart, to evolve similar abilities. Pterosaurs—fuzzy, flying reptiles that were related to dinosaurs—reigned over the skies more than 50 million years before Archaeopteryx, so it’s not as if Earth weren’t already full of fliers before dinosaurs caught on. The stories we now deduce of how flying dinosaurs gained their astonishing ability are far more complex than the ones we had even 20 years ago. When you see a house finch alight on a feeder or a turkey vulture slowly turn over a thermal, you’re catching a glimpse of one of the greatest secrets still cached in the fossil record.

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A newly discovered early bird-like dinosaur species is filling in some of the holes in the dinosaur-to-bird evolutionary story. The new species, named Fujianvenator prodigiosus, has a strange mixture of physical features shared with other extinct prehistoric animals from therapod dinosaurs to birdlike troodontids. This unique beast was described in a study published September 6 in the journal Nature. 

[Related: Birds are dinosaurs, and this fossil detective has rooms full of bones to prove it.]

Birds diverged from theropod dinosaurs by the Late Jurassic (about 161 million to 146 million years ago), but the general understanding of the earliest evolution of the clade comprising most modern birds, known as Avialae, has been slowed due to a limited diversity of fossils from the Jurassic. No known avialans have been reported from the Yanliao Biota paleontological site in northeast China, which dates back to the Middle–Late Jurassic about 166–159 million years ago or in the the slightly younger German Solnhofen Limestones, which preserves an early genus of avian dinosaurs called Archaeopteryx. This leaves a gap of about 30 million years before the oldest known record of Cretaceous birds. 

Jurassic era avialans are a critical key to deciphering the evolutionary origin of the avialan body,  and this elusive group is key to piecing together the origin of birds. That’s where the fossilized remains of the 148 to 150-million-year-old avialan theropod Fujianvenator prodigiosus comes in. It has some physical traits shared with extinct avialans, the small and bird-like troodontids that lived during the Cretaceous Period, and theropod dinosaurs called dromaeosaurids that were similar to raptors and also lived during the Cretaceous. According to the team on this study, this mixture shows the impact of evolutionary mosaicism–different rates of evolutionary change in body structures and function– in early bird evolution.

A joint research team from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences in Beijing and the Fujian Institute of Geological Survey (FIGS) described and the avialan theropod that was found in Zhenghe County, Fujian Province in southeastern China.

“Our comparative analyses show that marked changes in body plan occurred along the early avialan line, which is largely driven by the forelimb, eventually giving rise to the typical bird limb proportion,” study co-author and paleontologist Min Wang from IVPP said in a statement. “However, Fujianvenator is an odd species that diverged from this main trajectory and evolved bizarre hindlimb architecture.”

[Related: Birds are so specialized to their homes, it shows in their bones.]

During the Late Jurassic-Early Cretaceious, southeastern China saw some intense tectonic activities that resulted in a lot of movement of magma below the Earth’s surface. This created some deep basins with the Earth including where Fujianvenator was found.

Fujianvenator prodigiosus was likely about the size of a present day pheasant and had a tibia (lower leg) that is twice as long as its femur (thigh), which is a previously unknown condition for non-avian dinosaurs. This suggests that the bird was either a high-speed runner or a long-legged wader and it likely lived in swamps. This new finding contrasts with other early avialans, which are believed to have been more tree and sky-dwelling.  

Fujianvenator’s remains were found among a diverse collection of vertebrate fossils dominated by aquatic and semiaquatic species, including turtles and ray-finned fish. The authors named this fossil collection the Zhenghe Fauna. This diverse array of inhabitants and environment suggests that it was the site of emerging Jurassic vertebrate fauna around the time when Fujianvenator was there. This find and timing fills in an important gap in our understanding of ecosystems in Late Jurassic Northeast Asia and the team plans to continue to explore Zhenghe and other nearby areas.

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While the big boy dinosaurs like the Triceratops and Tyrannosaurus rex dominated North America and still get most of the attention from today’s movies, they were not the only dinosaurs on Earth. Some of their very distant relatives actually called Europe home. These animals were much smaller than their American cousins, but are getting some renewed attention. A new paper recently published in the journal Fossil Record delves deeper into the lives of these island-dwelling dinos. 

[Related: A giant new spinosaur species has been unearthed in Spain.]

Between 100 and 66 million years ago (also known as the Late Cretaceous), Europe looked very different than it does today. The present day continent was actually an archipelago consisting of large and small islands in a shallow tropical sea. Partially due to their isolation on these islands, the dinosaur groups that lived here were different from those on the mainland. They included small and medium theropods, the feisty and armored ankylosaurs, sauropods with their signature long necks, duck billed hadrosaurs, and rhabdodontids.

According to the study, the Rhabdodontidae family was a critical group in the Late Cretaceous European Archipelago. It includes generally small to medium-sized—at least by dinosaur standards—herbivores that were about 6.5 to almost 20 feet long.

“They were probably habitually bipedal herbivores, characterized by a rather stocky build, with strong hind limbs, short forelimbs, a long tail, and a comparatively large, triangular skull that tapers anteriorly and ends in a narrow snout,” study co-author and University of Tübingen vertebrate paleontologist Felix Augustin explained in a statement. “They had a relatively robust skull with strong jaws, large teeth and a pointy beak that was covered in keratin, demonstrating that these dinosaurs were well-adapted to eating tough plants.”

There is also some evidence that they were rather social animals, as the fossilized remains of several individuals of different ages have been found grouped together. Fossils of rhabdodontids, or “rod tooth” dinosaurs, have also only been found in Europe in rocks going back 86 to 66 million years ago, suggesting they were endemic to the Late Cretaceous European Archipelago. 

Scientists have found fossils from nine different species from France, Spain, Austria, Hungary, and Romania.

“The first rhabdodontid species was scientifically named more than 150 years ago and the last one as recently as November 2022, so, although the group looks back to a long research history, we still have much to learn about it,” Augustin said. “Generally, our portraying of the world of dinosaurs is heavily biased towards the well-known North-American and Asian dinosaur faunas.”

[Related: Were dinosaurs warm-blooded or cold-blooded? Maybe both.]

The rhabdodontids in Western Europe died out 69 million years ago, possibly due to environmental shifts that affected the plants they ate. However, those in Eastern Europe survived for millions more years and were among the last non-avian dinosaurs still present before the end of the Cretaceous Period.

Dinosaur fossils dating to the Late Cretaceous are more rare in parts of Europe than in North America or Asia, and scientists are still on the hunt for a complete rhabdodontid skeleton. Even though they were abundant during the Cretaceous of Europe, paleontologists are still puzzled by more specifics of their body proportions, posture, locomotion, and feeding behavior.

“In the past decades, a wealth of new, and often well-preserved, rhabdodontid fossils has been discovered throughout Europe, the majority of which still remains to be studied,” Augustin said. “A joint research project is currently underway to study the available fossil material in order to gain new insights into the evolution and lifestyle of these fascinating yet still poorly known dinosaurs.”

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Paleontologists have found fossils of two new species of some of Tyrannosaurus rex’s cousins in Morocco. Like the famed T. rex, these early relatives had short bulldog-esque snouts and even shorter arms. These new species appear to have primarily lived in southern latitudes unlike the T-rex, but ate mostly meat like its cousins. 

The findings were described in a study published August 23 in the journal Cretaceous Research. Both new species belong to the family Abelisauridae. The carnivorous abelisaurs were counterparts to the tyrannosaurs about 66 million years ago, towards the end of the Cretaceous period.

[Related: The T. rex ‘dynasty’ reigned for more than 125,000 generations.]

The fossilized remains were found in Sidi Daoui and Sidi Chennane, just outside of the city of Casablanca in Morocco. One of the yet-to-be-named species was found via a foot bone that indicates the predator was about eight feet long. The other new species left behind a shin bone that indicates the dinosaur was about 15 feet long. 

They lived alongside a much larger abelisaur called Chenanisaurus barbaricus. The discovery of these slightly less evolved abelisaurs show that Morocco was home to many different kinds of dinosaur species just before an asteroid struck the Earth near Mexico. The asteroid strike famously triggered the mass extinction that wiped out the dinosaurs and about 90 percent of the Earth’s species 66 million years ago.  

“What’s surprising here is that these are marine beds,” University of Bath paleontologist and evolutionary biologist Nick Longrich said in a statement. “It’s a shallow, tropical sea full of plesiosaurs, mosasaurs, and sharks. It’s not exactly a place you’d expect to find a lot of dinosaurs. But we’re finding them.”

According to Longrich, while dinosaurs account for only a small proportion of fossils found in the region, the area has still produced the best idea of what dinosaurs in Africa were living at the before they went extinct. Instead of finding the same few species in the area, paleontologists can often recover fossils from new species, a sign that the fossil beds were once home to a wide range of different dinosaurs. 

A small number of the dinosaur fossils that have been recovered here represent five different species–the giant abelisaur Chenanisaurus, a long-necked titanosaur, a small duckbill dinosaur named Ajnabia, and these two new abelisaurs.

“We have other fossils as well, but they’re currently under study. So we can’t say much about them at the moment, except that this was an amazingly diverse dinosaur fauna,” said Longrick

For over 200 years, scientists have debated the pattern of the end-Cretaceous extinction event. While the giant asteroid impact has been linked to their demise, there is evidence that some dinosaurs were already declining when the space rock crashed into Earth. 

[Related: The Sahara Desert was once flooded with history’s most vicious dinosaurs.]

The T. rex’s that lived in present-day Montana and Wyoming may have been one of the dinosaurs already in decline. According to Longrich, that only shows a small picture of one part of the world, so it is difficult to generalize how dinosaurs living on the other side of the planet were doing. Towards the end of the dinosaurs reign, temperatures around the world dropped and dinosaurs living at higher latitudes may have become less divergent as a result.  

At least in Morocco, dinosaur species seem to have remained successful and diverse up until the very end. 

“When T. rex reigned as a megapredator in North America, abelisaurs sat at the top of the food chains in North Africa,” Nour-Eddine Jalil, a co-author of the study professor at the Natural History Museum and a researcher at Universite Cadi Ayyad in Morocco, said in a statement. “The dinosaur remains, despite their rarity, give the same messages as the more abundant marine reptile remains. They tell us that, just before the Cretaceous-Paleogene crisis, biodiversity was not declining but on the contrary, was diverse.”

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As if the thought of a flying pterosaur with a 6.5 foot wingspan dominating Earth’s skies wasn’t terrifying enough, paleontologists have now found an even older pterosaur ancestor with some prominent claws. The latest find might not have its signature wings just yet, but boasts a beak and sharp claws. The roughly 230-million-year-old lagerpetid unearthed in Brazil is described in a study published on August 16 in the journal Nature. 

[Related: This pterosaur ancestor was a tiny, flightless dog-like dinosaur.]

Pterosaurs and dinosaurs both evolved about 235 million years ago in the Middle to early Late Triassic (about 235 million years ago). Dinosaurs went on to dominate the land during the Jurassic Period (201.3 to 145 million years ago) and the winged pterosaurs took over the skies during the Cretaceous Period (145.5 to 66 million years ago). 

While some new discoveries including finding Scleromochlus taylori in 2022 have filled in evolutionary gaps and helped paleontologists learn more about these winged critters, the fossil record from this time still remains relatively scarce. Lagerpetids like this newly discovered clawed specimen are the closest known non-flying group to pterosaurs.

In this new study, a team describes the well-preserved partial skeleton of a lagerpetid that they named Venetoraptor gassenae. The team estimates that V. gassenae would have been about 27.5 inches tall and about 39 inches long. The bone features indicate that this particular animal was an adult when it died. It also had feather-like fur on its body and a long tail.

“Because cranial remains are so scarce for lagerpetids, this is the first reliable look into the face of these enigmatic reptiles,” study co-author and paleontologist Brazil’s Universidade Federal de Santa Maria Rodrigo Müller told Gizmodo. “The unusual skeleton of Venetoraptor gassenae reveals a completely new morphotype of pterosaur precursors.”

V. gassenae’s more notable features include a raptorial-like beak and large hands with claws that resemble a curved sword. The team believes that the Veneraprot was highly specialized to its ecological niche. Its claws may have helped it climb or handle its prey, and V. gassenae also has an elongated fourth digit on its fossilized right hand. According to Müller, this has not been seen in other lagerpetids, which hints that V. gassenae is especially closely related to pterosaurs.

[Related: Dinosaur Cove reveals a petite pterosaur species.]

“This elongated fourth digit supports the wings in pterosaurs, so V. gassenae may represent the transition of lagerpetids towards pterosaurs,” Müller told LiveScience.

It’s unclear what role that its long beak played. Beaks obviously can help animals eat, but they can also have many functions beyond feeding, including sexual displays, vocalization, and regulating body temperature. 

By studying this fossil alongside the remains from 18 dinosaur and 10 pterosaur species from this time period, the team believes that lagerpetids were as morphologically diverse as Triassic pterosaurs and even more morphologically diverse than Triassic dinosaurs. It shows that this level of biodiversity was already starting to flourish in the precursors of both dinosaurs and pterosaurs and was not something that only emerged after both groups originated. 

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Oh, the wonders scientists see in the field. Documenting the encounters can be an integral part of the discovery process, but it can also pull others into the experience. These seven photos and illustrations are the winners of this year’s BMC Ecology and Evolution image competition, which gets submissions from researchers all around the world each year. It includes four categories: “Research in Action,” “Protecting our planet,” “Plants and Fungi,” and “Paleoecology.”

See the full gallery of winners and their stories on the BMC Ecology and Evolution website. And explore last year’s winners here.

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THERE ARE BONES EVERYWHERE. Black- and purple-painted models of the horn-faced carnivore Ceratosaurus nasicornis lie arranged by anatomical element in boxes. The cranium of a crocodile-like creature called a phytosaur rests on a worktable. Skeletons of dinosaurs, prehistoric mammals, and other wonders are stacked floor to ceiling in a storeroom. Past it, a Utahraptor ostrommaysi stands midkick, and the massive skull of the three-horned dinosaur Torosaurus waits to be fitted on a body. An artist grinds away at the head of the massive armored fish Dunkleosteus, sanding down its seams.

None of the bones scattered in plain view have been excavated from the ground. They’re resin likenesses that lead many a visitor to wonder aloud, “Are those fakes?” when exploring halls of strange and posed prehistoric skeletons. The answer is usually more complicated than viewers realize—and this busy fossil reconstruction studio in Fruita, Colorado, illustrates that perfectly.

Most people think of museums as hallowed strongholds of authentic dinosaur specimens. Each towering Tyrannosaurus or stupendous sauropod embodies life, death, extinction, survival, and, thanks to Hollywood, the enduring quest of sunburned explorers searching distant deserts. A replica doesn’t deliver that same gut punch of wonder. But that has more to do with our own misconceptions than it does with scientific reality.

Consider Sue the T. rex, arguably the most famous fossil dinosaur in the world. Standing in its own exhibit in Chicago’s Field Museum, Sue represents at least 80 percent of a full skeleton, making it the most complete specimen ever found of a “tyrant lizard king.” But paleontologists had to fill in the missing pieces with casts of other T. rex specimens they dug up. Sue’s real skull sits in a separate case on the floor, making it look as if the fossil was somehow in a car wreck. The piece is crushed and distorted from about 67 million years of sitting under layers of heavy sandstone. The pristine, grinning head seen on display is a scientifically informed artist’s impression of what the living animal looked like.

Fossil curators often stress the difference between casts and the originals, emphasizing the importance of making copies for display. The Field Museum, Australia’s Museums Victoria, and England’s Oxford University Museum of Natural History all try to get ahead of the “Is it real?” question on their websites. In 2018, London’s Natural History Museum sent its iconic cast of Diplodocus, “Dippy,” on tour, leading some commenters to surmise with shock that the renowned dinosaur had always been a fraud. “Let’s face it,” one Huffington Post commenter sneered, “Dippy isn’t even a dinosaur. She’s a fake.” And it’s not just Dippy—another take from a paleontology educator on reconstructed dinosaurs conceded that “even the best fossil casts are going to lack a certain something that the original fossils have,” though the article failed to dig into what that je ne sais quoi might be. Kids seem to be especially hung up on whether a bone was once part of a real animal or not. In a 2018 study in the International Journal of Science Education, Part B, one child told surveyors that dinosaur casts were “not as special” as original fossils “’cause, eh, you just know that it’s…a piece of plastic or something.’”

That same kid would probably find most genuine skeletons a letdown. Paleontologists occasionally uncover a dinosaur from volcanic ash and other sediments with every bone preserved perfectly in place, but most fossil animals are unearthed incomplete or damaged. If excavators simply freed them from their encasing rock and put them on display, museum patrons would be left scratching their heads over jumbles of weathered, flattened, and broken bones. 

Casts and replicas bring flawed skeletons closer to what they looked like in real life. So they’re just as important to paleontologists as to they are the public. Reconstruction expert Rob Gaston notes that most of the specimens he receives at his workshop, which he opened 27 years ago with his partner Jennifer Schellenbach, would not be presentable without artistic intervention. The scraps are a far cry from the majestic creatures so many museum visitors hope to see. Liberating fossils from rock is only the first step in bringing a long-extinct animal back to something resembling life.

“Really, the process is twofold,” the artist says as the team at Gaston Design bustles around the maze of tables and cabinets. “The first thing we do is obtain pieces from the museum. Those are usually incomplete, broken, distorted.” It’s like receiving a hand-me-down puzzle with only half the pieces in the box—many of them in sorry shape. 

The process doesn’t end with casting and correcting the original material. Whether a dinosaur is standing stock-still or running with jaws agape towards visitors, each reconstruction needs a metal armature that sits inside like a second skeleton. What’s more, the mounts have to be sanded down to remove seams, painted to look like the original rock, and assembled into their full forms before they leave the shop. The result is always something you can envision wrapped in muscle, scaly skin, and feathers.

THE SCIENTIFIC COMMUNITY hasn’t always had artists like Gaston on hand to fix and fit together those jumbled puzzle pieces. The way paleontologists reconstructed fossil skeletons through much of the 20th century is a perfect example of how even real bones can warp reality. In the bright halls of the American Museum of Natural History in New York City, for example, the iconic Triceratops that’s been tilting its horns at visitors since 1923 is a composite of several different individuals of roughly the same size. Likewise, most bones found in the Ice Age asphalt seeps of Los Angeles’ La Brea Tar Pits turn up jumbled. The chocolate-colored skeletons standing in the site’s museum have been pieced together from parts that don’t always fit. If a skeleton is reconstructed from the bones of several animals that lived in different geographic localities, and perhaps even disparate slices of time, should it count as real? 

Attempts to reconstruct what paleontologists uncover from Earth’s geologic record are about as old as the field itself. English paleontologist Richard Owen once mused that plaster copies of fossils might stoke wonder in museum visitors. In 1868, the English artist Benjamin Waterhouse Hawkins worked with Edward Drinker Cope and Philadelphia naturalist Joseph Leidy to create a complete reconstruction of Hadrosaurus foulkii, a herbivorous dinosaur that had been uncovered in the marl pits of southern New Jersey. The real bones were fragile and represented only a portion of the animal’s body, so the team made casts of what they had and sculpted the rest, creating the one and only mounted nonavian dinosaur at the time. The skeleton was a huge hit, perhaps inspiring the next generation of paleontologists to create additional reconstructions.

The popularity of more finished-looking fossils generated new questions—and problems—for museums. Creating and assembling casts was a laborious process, and the impression that visitors craved original bones led some institutions to put remains back together with materials like Bondo, an irreversible filler used on automotive and home projects, and to drill through specimens so they could be slotted onto permanent armatures. In time, paleontologists began to favor casts as replacements or complements, even as some in the scientific community saw reconstructions as second-rate.

“I think calling them ‘fakes’ or regarding them as inauthentic doesn’t appreciate how much preparation, construction, and modeling goes into making real fossils into objects that are usable for scientific research or display,” says Chris Manias, a paleontology historian at King’s College London. Instead, casts and reconstructions exist along a continuum, he notes, filling in the gaps on mounts when needed, or standing in for missing fossils entirely. 

Manias also disagrees that these thoughtful imitations reduce the wonder inspired by prehistoric creatures. “Casts and reproductions have always remained highly important,” he says, a fact underscored by recent exhibits of a long-necked herbivore called Patagotitan mayorum at several large museums in the US and England. This dinosaur, made of casts from multiple incomplete skeletons, stretches to more than 100 feet long, making it among the largest prehistoric reptiles described by paleontologists. At such stupendous size, awe erases any quibbles about authenticity.

AT THE FRUITA STUDIO, Gaston and his crew of artists excel at blending fact and speculation. While Gaston has done some repair work on original fossils, particularly for commercial dealers, he spends most of his time visualizing what fossils looked like when they were still fresh and unscathed, filling in missing skeletal parts to create exhibit-worthy animals for universities and museums. 

Everything starts at the casting station, which sits just a few steps inside the workshop door. Copying specimens can be a precarious process given the fragility of most fossil bone. The key is silicone. Placed within a cushioning cradle—with special armatures made for skulls or other large pieces—the fossil is doused in a cloudy, slimelike liquid polymer that is then left to cure. Gaston and his colleagues peel the soft shell away once it’s dry, creating a mold. “Your piece comes out, hopefully without damage,” Gaston says, or at least nothing that can’t be easily repaired. Chips and cracks aren’t unusual. Such a risk might surprise members of the public, but specimens face similar threats at every stage from excavation to display. Experts often break fossils in the field, the lab, and museums. Scientists and preparation specialists have devised all sorts of adhesives and strategies to extend the afterlife of ancient bone, including an entire line of fossil-ready superglues called PaleoBond.

Gaston estimates that most of the skeletons he works on require between 100 and 150 distinct molds, which are stored in an on-site warehouse. The resin casts created from those molds are just the beginning of the reconstruction process. The phytosaur skull sitting on Gaston’s workbench is part of one such project: a beautifully complete cranium of a crocodile-like reptile with sharp teeth about as big around as a human thumb, discovered by paleontologists from the St. George Dinosaur Discovery Site museum in Utah. Sometime after the animal’s death about 220 million years ago, something smashed the skull. “As you can see, it’s really, really distorted on one side,” Gaston notes, “so while this is a nice, fairly complete skull, it’s going to need extensive work.” He created a replica from the phytosaur’s mold that he can cut apart, sculpt, and otherwise fix to look like natural, symmetrical bone and not a Triassic pancake. 

Restoring an animal that lived thousands, millions, or tens of millions of years ago is a huge challenge. There are usually no fresh skeletons to compare the reconstructions to for accuracy. Unless paleontologists find a complete, undistorted head, it can be challenging to tell a species’ actual proportions—how far the back of the skull flared out, or the exact position of the nasal openings. The large Torosaurus lying on the workshop floor, for instance, came from a young creature whose bones had not yet fully fused. The skull was in fragments when Gaston began working on it, a three-dimensional puzzle put together according to the anatomy of more mature horned dinosaur specimens. Closely related species can have the same individual bones in their skulls, but with slight variations, and can provide a basic guide to what should fit where. The goal, Gaston says, is to do as little as possible and not over-sculpt such reconstructions. A touch of asymmetry in an otherwise beautiful fossil is better than perfection, which can look unnatural.

At every step of his weekslong process, Gaston keeps museum visitors in mind. “The conundrum you get in is you want to present a cast as close as it can be of what was found, but if it’s a public display piece, you want it to be anatomically something [people] can understand and relate to,” he says. It’s a difficult balancing act, trying to fairly represent the animal while still retaining the texture, color, and overall shape of the fossil. “It’s kind of like refinishing an antique, where you might fix broken parts but you don’t strip the finish off and rebuild,” Gaston explains. 

Still, the inference and guesswork involved is often invisible to the public—and even to artists who base their illustrations on fossil reconstructions. While working on a relatively new dinosaur from Utah, Nasutoceratops titusi, Gaston had to contend with the fact that the dinosaur’s skull was crushed and the horns were bent down, almost like a longhorn cattle’s. He decided against cutting the cast apart and rearranging the horns, leaving them relatively flat instead of angled up. Some decisions have more to do with design or reconstruction capabilities than anatomical certainty. But artistic re-creations of Nasutoceratops have perpetuated the image and even exaggerated it, like a game of telephone stretching back millions of years.

Sometimes renderings can be corrected when new evidence turns up. Take Apatosaurus, which sported a deep and boxy head with spoonlike teeth until paleontologists unveiled the real thing in 1978: a wedge-shaped skull with short, pencillike teeth. In these cases, regular dinosaur nerds might think paleontologists are simply making things up. The cachet of authenticity creates a great deal of tension in planning what to present to the public.

“The main argument you hear is, ‘The public doesn’t want to see casts, they want to see real things,’” Gaston says. The primary counterpoint is that reconstructing and mounting original fossils can damage the bones in the process. But, Gaston also notes, most of the time the original fossils aren’t even fit to display. “Seventy to 75 percent of the material I deal with may be almost a complete skeleton, but it’s all so badly distorted or mashed that it’s not mountable.” Casting—both for reconstruction and for repairs—allows dinosaur and other paleontological exhibits to better show what was once inside living creatures. 

A FEW OF GASTON’S re-creations sit in Dinosaur Journey across town. Without casts, “there would be a lot more labels, a lot more signage trying to translate the fossil record,” says Julia McHugh, a curator at the museum. It would require a lot more patience from visitors, perhaps more than they would be willing to give, to explain the identity and orientation of original fossils. Instead, McHugh and other curators have often favored placing the original fossils next to reconstructions. “Then you can say, OK this is what the fossil looks like coming out of the ground; this is what the fossil would look like in life,” she explains. 

Over time, paleontologists have gotten better at collecting, constructing, and displaying natural specimens. Some of the grand skeletons in the Smithsonian National Museum of Natural History’s recently renovated Deep Time exhibit are made from original bone. But such undertakings have their own constraints. “It’s expensive; it takes a lot of time; it’s very heavy; and those things do not move,” McHugh says. That means a fossil skeleton of Diplodocus or Tyrannosaurus will have to stand in one spot for years, if not decades, rather than being part of a more modular museum that can change as the science does. A cast, she notes, can come apart in minutes—an advantage that facilities rely on to update their displays or even put on traveling exhibits.  

Downstairs from McHugh’s office at Dinosaur Journey, a Ceratosaurus the length of a large SUV stands posed like a cat about to jump on a windowsill. It’s the finished version of the cast in Gaston’s shop. The Jurassic carnivore’s back legs are flexed, and its long tail makes a sinuous S. Its resin jaws remain half open to let the exhibit lights gleam off dozens of re-created teeth. The replica was created using bits of fossil, resting in a nearby glass case, that were picked apart by looters in the nearby Fruita Paleo Area before paleontologists got to them. Its original skull was also flattened, with both sides of the upper jaw wrenched out of alignment. Casts of other Ceratosaurus bones helped fill in the missing parts. The limb bones and vertebrae of the reconstruction obscure the steel that now gives the animal its postmortem form. 

But what matters is that the beast looks alive. The sweep of the reptile’s tail almost begs for visitors to envision the muscles, tendons, blood vessels, and other soft parts that must have draped around that skeleton when its kind wandered fern-covered flood plains. Somehow the human-made materials feel closer to the living animal than the degraded remnants of its ancient biomolecules.

The dichotomy between real and fake crumples when we encounter creatures that can be revived only through our imaginations. A paleontologist can certainly work from a collection of bones chipped out of the rock and come up with physical features and measurements, but such data often feels unsatisfying on its own. When those pieces mesh with our best guesses about missing bones, we can start to infer how big the animal was, how it might have acted, and what the Earth was like when we were nothing more than a distant possibility. These casts and reconstructions bring our dreams and nightmares from the Age of the Dinosaurs closer to existence. The dinosaurs we love to gaze at, with their mighty jaws and claws, don’t come to us straight from the rock, but truly come to life in a workshop off a rural Colorado road. 

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Picture this: Two dinosaurs with massive teeth and hulking figures circle each other, threatening a smackdown. Each was the most successful predator of its time. In a ferocious duel of the dinosaurs—Tyrannosaurus rex vs. Giganotosaurus carolinii—which would emerge alive? 

Both species enter the ring with experience as apex predators that hunted some seriously impressive prey. T. rex is thought to have eaten armored Triceratops and big-brained duck-billed dinosaurs, while Giganotosaurus probably took down the largest-ever land animals: the long-necked sauropod dinosaurs, which could’ve been 10 times the predator’s size. None of these dinos would’ve been an easy meal. So what would happen if the two fearsome Cretaceous carnivores were to face off against each other?

But pitting the two against each other serves to highlight their differences, says Thomas Holtz, a principal lecturer in vertebrate paleontology at the University of Maryland who studies tyrannosaurs and their motion. This kind of thought experiment might lead to a better understanding of how these creatures followed their own evolutionary paths to become distinct, highly successful predators. 

Some of those differing characteristics might be advantageous in a rumble. But in a one-on-one fight, there is unlikely to be an obvious champion and an underdog, says Kat Schroeder, a paleomacroecologist and postdoctoral research associate at Yale University.

“They’re not fighter jets,” she says. “You can’t say this one has this absolute top speed. They’re animals. And they’re animals that lived 30 million years apart on different continents. They’re separated by 150 million years of evolution [since their last shared ancestor].”

[Related: Jurassic Park fans would love these dino discoveries]

Holtz agrees that it could be any dinosaur’s game, despite admitting professional and personal bias toward tyrannosaurs (when he was 3, he wanted to grow up to be one). “Both of them are big predators adapted to killing very large prey,” he says. “If either of them managed to get a good bite onto the other one first, they’re probably going to win.” 

What’s in a bite?

T. rex and Giganotosaurus can be described as “head hunter theropods,” Schroeder says. They both had “teeny, tiny little arms and giant heads,” she says, “so they’re probably not going to be pulling and scratching at one another.” Kicking is also out, because their feet would probably be too heavy to be of use in a fight. So there’s only one remaining option with any teeth. “They’re basically going to walk up to one another and try to grab each other with their giant mouths,” she says.

Both predators’ bites are vicious in different ways. T. rex can deliver the most skull-crushing of chomps, while Giganotosaurus’ bite leverages sharp, blade-like teeth to slash its prey’s flesh. 

T. rex’s bite force is “almost off the scale,” says Holtz. The lowest estimates for an adult’s bite force are around 34.5 kilonewtons, he says, “which is twice as strong as the bite of a saltwater crocodile, the largest reptilian predator of today.” 

[Related on PopSci+: What dinosaur fossils are we missing?]

Several adaptations in a T. rex’s head enable that smashing crunch. For one, the tyrant lizard has a long, deep snout made up of thick jaw bones, with very deeply rooted teeth. From above the gums, T. rex and Giganotosaurus would’ve appeared to have the same size teeth. But the roots of T. rex’s teeth, Holtz says, were double those of a Giganotosaurus tooth, which could be around 8 inches in total length. The largest known T. rex teeth reach 12 inches, and they’re built for impact with a round, thick shape. “T. rex has a jackhammer for a mouth,” Schroeder says. 

The T. rex’s snout was also made up of somewhat flexible bones, Schroeder says, which can be an advantage for a big bite. “A little bit of springiness allows you to bite really, really hard without breaking your own face.” 

Giganotosaurus, on the other hand, had a more forceful nip at the front of its mouth, with a long and slender snout about three times as long as it was tall. Its sharp, blade-like teeth were better at cutting than chomping down. Giganotosaurus teeth could ably slice through meat and might have been able to cause a lot of damage with a small nip.

But these dinosaurs likely wouldn’t just take turns biting each other, even locked in a cage fight. Their body size and nimbleness would also come into play.

Agility of the fighters

Jurassic Park’s Alan Grant was incorrect when he said Giganotosaurus was the largest carnivore ever to roam the Earth (that crown goes to Spinosaurus), but it was likely larger than a T. rex—at least in length. Giganotosaurus was probably about 45 to 47 feet long, while the largest T. rex specimen reached nearly 42 feet long (nicknamed “Scotty,” its bones reside at Canada’s Royal Saskatchewan Museum). Both stood about 20 feet tall, and Giganotosaurus may have had a few tons of mass on T. rex, but estimates for their maximum masses are both upward of 9 tons. 

Still, it’s unlikely that such a small size difference would give one dinosaur an edge over the other, says Holtz. What might have put T. rex in the lead, he says, was its weight distribution and resulting agility.

T. rex’s weight is concentrated toward its middle, while Giganotosaurus is “more long and slab-like throughout its body,” he says. Holtz and colleagues calculated that a T. rex could rotate its body and twist in place twice as well as other dinosaurs of a similar mass, thanks in part due to massive hip bones and muscles. The pyramid-shaped ankle bones of a T. rex also may have offered more stability for maneuvering than a Giganotosaurus’s boxier ankles, Schroeder says. “T. rex might have been able to corner a little bit better.”

Two aspects of tyrannosaurus’s evolution might explain these adaptations, Holtz suggests. T. rex’s ancestors were smaller—the ones that were around when Giganotosaurus roamed Earth were “basically dinosaurian coyotes,” he says. Or perhaps they evolved these traits to take down sophisticated prey. Triceratops, for example, was “one of the most heavily armed herbivores in Earth history,” he says, and duck-billed dinosaurs had one of the largest brain-to-body size ratios of any herbivorous dinosaur. T. rex had a bigger brain than Giganotosaurus, Holtz says, probably because it had to hunt speedier, more agile prey.

Giganotosaurus brains were half the size. “You don’t have to have a lot of focus if you’re going after walking walls of meat,” Holtz says. They came from a long line of giant predatory dinosaurs. Their “basic body plan” prepared them to hunt “long, slow-moving” herbivores, such as stegosaurs and sauropods.  

[Related: The longest dinosaur neck ever found in the fossil record]

Defeating a sauropod, which lived in a pack and may have grown up to 80 tons, would not have been easy, however, says Schroeder. Even picking off a small, young herbivore would’ve been tricky. “You’re not rolling up on a group of elephants and just grabbing a juvenile,” she says.  “You’re going to have to face off with one of these enormous animals.” 

It’s possible that this is where the slashing kind of bite comes in handy for Giganotosaurus, Holtz says. Maybe it could deliver a fatal bite quickly, he says, or perhaps its blade-like teeth could weaken the massive prey, so the carnivore could track it down to go for the kill at the right moment. 

That might be how Giganotosaurus could get the first bite on T. rex, too. The tyrant lizard had both of its eyes on the front of its face, offering better depth perception, Holtz says. But Giganotosaurus’s eyes, more toward the sides, gave better perception around their bodies. The giant southern lizard might be able to sneak-attack the T. rex, sinking its sharp front fangs into its opponent’s flank. 

If the battle occurred in one of the creatures’ home habitats, instead of in a neutral environment, that would add another dimension, Schroeder says. On Giganotosaurus’ turf, for example, T. rex might struggle with the heat and dryness of the desert in what is present-day Argentina.  

These environments, and the prey who lived there, shaped how these dinosaurs evolved. During Giganotosaurus’s time, the environment was changing dramatically with the emergence of diverse flowering plants. By the time T. rex came on the scene, however, the environment was much more stable—right up until a big rock smashed into the planet. 

There’s also a lot that remains unknown about both dinosaurs, but especially Giganotosaurus, Schroeder says. Paleontologists have found fewer of its fossils, and discuss it less frequently at conferences, likely because its homeland of South America gets less scientific attention and funding. “Paleontology tends to be a little bit North America-centric,” she says. And while “it’s fun to talk about these questions” of who would win in a fight, “we wouldn’t have any answers if we didn’t have fantastic scientists working down in South America and Africa.”

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Paleontologists have uncovered a new species of dinosaur that grazed along the grasslands of Thailand about 145 to 200 million years ago. Minimocursor phunoiensis lived during the late Jurassic age, and its well preserved fossilized remains were uncovered in northern Thailand’s Phu Kradung Formation.

[Related: Bite marks on Triassic fossils show signs of bloody dino decapitation.]

The findings were published earlier in July in the open-access journal Diversity.

“The Phu Noi locality contains a wealth of specimens and has yielded an exceptionally articulated skeleton, which represents one of the best-preserved dinosaurs ever found in Southeast Asia,” the team wrote in their conclusion. “This is the earliest record of neornithischians in Southeast Asia, and the first dinosaur taxon named from the Phu Kradung Formation of Thailand.”

Neornithischia is a clade of primarily plant eating dinosaurs that counts ornithopods, marginocephalians, and some small bipedal dinosaurs among its ranks. 

The team first uncovered the remains in 2012 and analyzed the fossils for over six years before officially concluding that the remains belong to a whole new species of dinosaur. They looked at 225 characteristics of the skeleton, and found roughly five unique traits in M. phunoiensis’ hips, face, and hands. It had a distinctive small bony lump on its jaw and an uncommon flange on the pubic bone.

Study co-author Sita Manitkoon from the Palaeontological Research and Education Centre at Thailand’s Mahasarakham University, told the Australian Broadcasting Corporation that this was a unique find. “It’s one of the most complete skeletons. Previously, Thai dinosaurs, they usually find isolated bones, just some leg bones, some vertebrae, something like that. But in this case, we found a whole articulated skeleton, so it’s very special,” Manitkoon said.

Based on the dinosaur’s tooth records, it was an herbivorous dinosaur. It was also likely a common and widespread animal, as at least 10 different specimens were found together at the site, according to Manitkoon.

[Related: This badger-like mammal may have died while trying to eat a dinosaur.]

As they reached adulthood, M. phunoiensis could have grown to about 6.6 feet long, based on a 10 inch femur bone. This would make them as long as a present-day llama or lion. With their relatively small stature and some signs that they adapted to be fast runners, they earned the name Minimocursor, or “smallest runner” in Latin.

Paleontologist Darren Naish at the University of Southampton in the United Kingdom told New Scientist that Minimocursor appears to sit on a branch of the family tree where roughly all the dinosaurs hail from eastern Asia, ranging from Thailand in the south to Siberia in the north. Naish added that this region of the world has the potential to reveal well-preserved remains like this one, so more discoveries in the area could be on the horizon. 

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Dinosaur Mysteries digs into the secretive side of the “terrible lizards” and all the questions that keep paleontologists up at night.

WE ALL KNOW about the asteroid. Close to 66 million years ago, during spring in the Northern Hemisphere, a 6-mile-wide chunk of space rock slammed into our planet and set off the world’s fifth mass extinction. Around 75 percent of all existing plant and animal species vanished almost overnight, and our beloved dinosaurs were decimated. Of the dinosaurian herd, only beaked birds made it to modern times.

But we’ve been so focused on how the Age of Dinosaurs ended that their unexpected rise is often overlooked. Around 201 million years ago, at the dawn of the Jurassic Period, a different mass extinction allowed dinosaurs to become the “terrible lizards” we so adore. Of the five mass extinctions that paleontologists recognize, it was the fourth that truly set the stage

The idea of dinosaur “dominance” is so commonplace that it’s strange to think there was a time in the distant past when the reptiles were not large and in charge. Yet that is exactly what paleontologists have discovered. The oldest dinosaurs we presently know of, from Triassic rocks dating to more than 230 million years ago, were relatively small, slender creatures who were rare compared to the other animals of the ancient landscape. The recently named Mbiresaurus raathi from Zimbabwe, for example, was a bipedal herbivorous dinosaur about the size and weight of a German shepherd, far from the largest or most ferocious creature of its time.

The Triassic saw different families of reptiles thrive. A mass extinction at the beginning of the period, caused by massive volcanic outpourings in what’s now Siberia, spurred rapid global warming, changes in atmospheric oxygen levels, and other ecological havoc that pushed the scaly creatures to evolve in new ways or go extinct. The first dinosaurs that evolved in the aftermath were slender, omnivorous creatures about the size of a labradoodle. But the reptiles that left the biggest mark on the landscape were ancient cousins of today’s crocodiles—a group called pseudosuchians.

Over the past two decades, paleontologists have uncovered multiple pseudosuchians that evolved dinosaur-like anatomies and behaviors long before actual dinosaurs did. The boxy-headed carnivore Postosuchus looked so much like a Tyrannosaurus rex that it was initially mistaken for a T. rex ancestor rather than the crocodile it is. The small herbivore Effigia okeefeae ran on two legs and had a beak rather than teeth, resembling “ostrich mimic” dinosaurs like Struthiomimus altus, a species that would evolve over 100 million years later. The thick-plated “armadillodiles” Desmatosuchus were pseudosuchians too, pioneering a spiky style that would later be reinvented by ankylosaurs. Prehistoric crocodiles came in every shape and size in the Triassic, while dinosaurs were mostly small, svelte, and not all that anatomically remarkable. Some were starting to get big by the end of the period, but they were nothing like the marvelous oddballs we saw in the Jurassic.

But by the 1950s, paleontologists noticed that many of the Triassic animal groups they had uncovered had disappeared by the earliest days of the following period, the Jurassic. The vast majority of the diverse pseudosuchians vanished, while dinosaurs seem to persist through the Triassic-Jurassic boundary almost unscathed. Experts have proposed everything from changing sea levels to an earlier asteroid impact to explain the biodiversity shake-up, though the most likely culprit is another intense bout of volcanic belches in the sprawling Central Atlantic Magmatic Province. The eruptions happened when the supercontinent Pangaea was just breaking up, but we can get an idea of the areas affected by looking at preserved volcanic rocks in the jigsaw of today’s continents. Traces of the pulse, which went on for more than half a million years and increased global atmospheric carbon dioxide to levels 10 times higher than what we’re dealing with today, have been found from Nova Scotia to Brazil. And that’s hardly all. Geologists have also found evidence of sulfur dioxide in rocks from this critical time, compounds that would have caused rapid cooling in between warm spells created by greenhouse gases.

Why the protocrocs faded while dinosaurs shrugged off these changes is a mystery. On paper, you’d think that a group of animals that evolved a broader variety of shapes, sizes, and behaviors would fare better under pressure. While some crocs did persist, they were the small, relatively generalized carnivores that chased bugs and lizards rather than the large, intricate ones. Small opportunists tend to fare better through mass extinctions, as they’re able to find enough food and habitat while larger, more specialized animals struggle. But the fact that members of all three main dinosaur groups—the predecessors of the Allosaurus, Apatosaurus, and Stegosaurus genera—all survived seems strange when you consider the fate of their distant crocodilian relatives.

The secret may be found within tissues and biological systems that are more difficult to preserve than bone. In 2020, paleontologists described a close relative of the common ancestor of dinosaurs and the flying pterosaurs—a tiny reptile they named Kongonaphon kely. Such a small animal would have benefitted from its warm, fluffy protofeathers—a trait present in both dinosaurs and pterosaurs—and paleontologists suspect that small size, warm-bloodedness, and an insulating coat were inherited by the first dinosaurs. Those qualities would have allowed them to withstand a greater variety of habitats than their crocodile cousins.

The backstory makes a little more sense in light of new research shared last year. Fossils of early dinosaurs are sometimes found in habitats that would have been frozen for at least some parts of the year. Though prolific, pseudosuchians seem to have been distributed only through warmer areas while Triassic dinosaurs had a greater range, allowing them to persist through the shifting climates created by the incredible eruptions 201 million years ago.

Had those eruptions not occurred or had they been less intense, it’s possible that the “Age of Dinosaurs” might instead have been the “Age of Crocodiles.” Dinosaur evolution would have been shaped by interactions with a broader cast of pseudosuchians, making for an alternative universe we’ll never get to see. A pair of mass extinctions cleared the ecological decks and allowed dinosaurs to venture to places where they could prosper and adapt into new forms—a wistful contrast to their own disastrous moment many millions of years later.

We hope you enjoyed Riley Black’s column, Dinosaur Mysteries. Check back on PopSci+ in September for the next article.

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About 125 million years ago, a carnivorous mammal and a large herbivorous dinosaur were locked in a fight to the death. The strangest part, however, is that the mammal was likely the primary aggressor. This unusual fossil discovery is described in a study published July 18 in the journal Scientific Reports, and challenges the idea that dinosaurs fully dominated in the Creteceous period (145 million to 66 million years ago) and lacked threats from their mammal contemporaries.

[Related: The ancestor of all placental mammals survived the dino-killing asteroid.]

“The two animals are locked in mortal combat, intimately intertwined, and it’s among the first evidence to show actual predatory behavior by a mammal on a dinosaur,” co-author and Canadian Museum of Nature palaeobiologist Jordan Mallon said in a statement. 

The dinosaur in this fossil is a species of Psittacosaurus, which were herbivores that were roughly the size of a large dog. They are also among the earliest known horned dinosaurs that lived in present-day Asia around 125 to 105 million years ago. 

An extinct badger-like mammal called Repenomamus robustus is the aggressive mammal. While the creature was not large by dinosaur standards at about 26 to 31 pounds and only three feet long, it was still one of the largest mammals of the Cretaceious period. Previously, paleontologists discovered that Repenomamus preyed on dinosaurs including Psittacosaurus due to clues left behind by the fossilized bones of baby dinosaurs found in the mammals’ stomach. 

“The co-existence of these two animals is not new, but what’s new to science through this amazing fossil is the predatory behavior it shows,” Mallon said.

The fossil in this study was unearthed in China’s Liaoning Province in 2012 and is now in the collections of the Weihai Ziguang Shi Yan School Museum in China’s Shandong Province. The skeletons of both animals are nearly complete, and they come from an area known as the that has been dubbed China’s Dinosaur Pompeii. Many of the fossilized mammals, lizards, dinosaurs, and amphibians that have been found there were buried following one or more volcanic eruptions. 

The fossil was in the care of study co-author Gang Han in China, who brought it to the attention of Canadian Museum of Nature palaeobiologist Xiao-Chun Wu. 

A close examination of the fossil shows Psittacosaurus is lying prone, with its hindlimbs folded on either side of its body, while Repenomamus coils to the right sitting on top of its prey and gripping the jaw of the larger dinosaur. The mammal is also biting into some of the dinosaur’s limbs and its back foot is gripping onto the dinosaur’s hind leg. 

“The weight of the evidence suggests that an active attack was underway,” said Mallon.

[Related: The fiery end of the dinosaurs kicked off the golden age of mammals.]

The team ruled out the possibility that the mammal was scavenging the remains of a dead dinosaur, partially because the bones of the dinosaur lack any known tooth marks. Additionally, it is unlikely that the two ancient animals would have become so intertwined if the mammal found the dead dinosaur.

They also note that smaller animals alive today are known to attack larger prey, such as some lone wolverines that are known to hunt caribou and domestic sheep. The wild dogs, jackals and hyenas of the African savanna are also known to attack when its prey that is still alive, which causes the prey to collapse out of shock. 

“This might be the case of what’s depicted in the fossil, with the Repenomamus actually eating the Psittacosaurus while it was still alive—before both were killed in the roily aftermath,” said Mallon.

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Dinosaur Mysteries digs into the secretive side of the “terrible lizards” and all the questions that keep paleontologists up at night.

WE’RE MORE THAN 66 million years too late to take a dinosaur’s temperature the old-fashioned way. Paleontologists can’t put a Tyrannosaurus rex under anesthesia and leave a wax-sealed thermometer inside the dinosaur’s body, as some zoologists did to track crocodile temperatures. While experts think that nonavian dinosaurs were active, fast-growing creatures with body temperatures that were higher than their surroundings, Dinosaur Physiology 101 is still a subject with more questions than answers. Those answers can shed light on everything from how much dinosaurs needed to eat each day to how they withstood environments ranging from Arctic forests to searing deserts.

Paleontologists have gone back and forth over the years on whether dinosaurs were warm-blooded or cold-blooded. During the late 19^th century, some scholars aptly guessed that dinosaurs were agile and on the move most of their lives. Their deductions were based in part on the limb proportions of prehistoric reptiles like the shovel-beaked Hadrosaurus foulkii and the sharp-toothed tyrannosaur Dryptosaurus aquilunguis, which indicated that these were busy animals rather than giant meandering lizards. But as the field of paleontology shifted its focus to evolutionary questions, researchers became more interested in the abundant, familiar fossil mammals rather than the strange and sometimes inscrutable dinosaurs. It took until the late 1960s—and the discovery of Deinonychus antirrhopus, the inspiration for Jurassic Park’s velociraptor—for paleontologists to revisit the idea that dinosaurs ran hot. The debate is still raging today.

Of course, it isn’t a simple question in the first place. The idea of being either warm-blooded or cold-blooded—a binary choice between one physiological profile and another—is a pretty flawed concept, limited to an organism’s body temperature rather than how its metabolism and physiology regulate that temperature. Consider a horned lizard scurrying around in the desert as the sun is coming up. Because it is “cold-blooded,” or what zoologists call ectothermic, the lizard’s body temperature shifts with its surrounding environment. This means the reptile will probably act sluggish in the cool of the morning but get much more active as the sun warms its spiky little body. “Warm-blooded” or endothermic creatures like humans, which maintain a near-constant and elevated body temperature, don’t have to thaw out in the sun, but also have to be careful not to overheat or exceed the narrow temperature range they can properly function in.

Then there’s the in-between. Some animals, including great white sharks, keep their bodies warmer than the surrounding seawater but still experience significant shifts in temperature as they move between warm and cold waters. Then there are marsupials that undergo daily torpor, a period when they are fully awake but physically inactive to conserve energy. Studies of a small, shrewlike animal called a planigale, for example, found that its body temperature dropped at least 6°F for up to 12 hours a day.

Even with all the wishy-washiness, there are some set biological factors that play into managing heat and related body functions. Mass seems to be a big one. In 1946, paleontologist Edwin Colbert and colleagues conducted a set of cruel experiments on alligators, exposing them to direct sunlight in apparatus that positioned the reptiles like tail-dragging dinosaurs. The larger alligators changed temperature more slowly, owing to the relationship between volume and surface area, but the smaller study animals had a harder time regulating their body temperatures. A few even perished from getting too hot in the unrelenting sun. But the study, and many others that came after it, showed that more mass means body temperatures change more slowly, requiring bigger animals to adopt strategies to gain or dump heat so they can stay comfortable.

Dinosaurs, like modern beasts, probably didn’t share one standard physiological profile. After all, the word dinosaur encompasses a huge, still-living group of animals of different shapes and sizes that have been around for more than 200 million years. But to investigate the internal thermostats of long-dead species like Triceratops and Allosaurus, paleontologists had to get inventive.

Some researchers have attempted to take dinosaur temperatures directly from fossilized bones. Organisms take in isotopes of oxygen when they drink water; as the element is incorporated into bones and teeth, its geochemical signature is modified by the body’s temperature. After applying the technique to T. rex, a 1994 study concluded that the dinosaur’s oxygen isotopes looked like those of a homeotherm—an animal that maintains a near-constant body temperature, usually as a result of generating internal body heat. But other experts questioned the results, and later analysis proposed that while T. rex generated its heat internally, it may have had a fluctuating body temperature like great white sharks today.

Interpreting the microscopic details of dinosaur skeletons has also been challenging because experts are still learning how physiology affects bone growth in living animals. Many ancient reptilian fossils show lines of arrested growth, or LAGs, created when the organisms periodically stopped maturing. These bone rings were once taken as a sign that nonavian dinosaurs periodically halted their growth, like many modern reptiles, and therefore might have been cold-blooded. But a 2012 study found that modern mammals create LAGs in their bones during cold seasons when food is scarce and going through a growth spurt isn’t the best option. Still, various studies of dinosaur growth rates have generally found that the  “terrible lizards” developed faster than living reptiles and even at rates comparable to those of living mammals. But the correlation is vaguer than the detailed information scientists have been seeking from fossils.

Paleontologists are still scraping together clues using various techniques as they try to come up with the big picture on body temperatures. One study from 2022 looked at biological markers of metabolic stress preserved in dinosaur bones that can act as clues to an animal’s metabolism. Big names like Tyrannosaurus and Brachiosaurus more closely matched endothermic animals studied today, while those like Stegosaurus and Triceratops seemed to have evolved from an endothermic ancestor but switched to be more ectothermic. Then again, a different analysis that looked at where long-necked dinosaurs like Brachiosaurus lived indicated that these dinosaurs never inhabited cold, polar environments, hinting that they had variable body temperatures and couldn’t withstand the cold like carnivorous theropods. In short, the available evidence doesn’t offer a straight answer just yet.

The good news is that we’re not teetering on the edge of a total dinosaur rethink. Experts have uncovered plenty of proof that our Mesozoic favorites were behaviorally complex animals that locked horns, bit each other on the face, dug after prey hiding in their burrows, and sometimes moved together in social groups. Dinosaurs generally grew up fast and, one way or another, maintained high body temperatures that required a lot of food to fuel. It’s the specific details that remain unclear, and they may be as different between any two dinosaur species as they are between any two mammal or bird species alive today.

We hope you enjoyed Riley Black’s column, Dinosaur Mysteries. Check back on PopSci+ in July for the next article.

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While humans and dinosaurs only co-existed in cartoons like The Flintstones, some of our very early ancestors potentially shared a brief moment with the likes of the Titanosaurs and the iconic Triceratops. These distant relatives also survived the catastrophic extinction event that was triggered by the asteroid that hit the Earth and wiped out non-avian dinosaurs, according to a study published June 27 in the journal Current Biology.

[Related: The fiery end of the dinosaurs kicked off the golden age of mammals.]

The study revealed that a Cretaceous origin for placental mammals, the diverse group that includes humans, dogs, and bats, briefly co-existed with dinosaurs before the dinosaurs went extinct. Placental mammals all bear live young that are nourished via an organ called the placenta in-utero.

On a spring day 66 million years ago, an asteroid struck the Earth near Mexico’s Yucatán Peninsula. The devastation in its wake wiped out all of the non-avian dinosaurs and many mammals, such as a rodent-looking animal named Vintana sertichi  that weighed up to 20 pounds and lived on Madagascar. Scientists have long debated if placental mammals were present with the dinosaurs before the Cretaceous-Paleogene (K-Pg) mass extinction, or if they only evolved after the dinosaurs died out. 

According to the team, the fossilized remains of placental mammals have only been found in rocks that are younger than 66 million years old. But molecular data has suggested an older origin for placental mammals.  

In this new study, a team of paleobiologists used statistical analysis of the fossil record to determine if placental mammals originated before this mass extinction event. They collected fossil data from placental mammal groups all the way back to 66 million years ago.

“We pulled together thousands of fossils of placental mammals and were able to see the patterns of origination and extinction of the different groups. Based on this, we could estimate when placental mammals evolved,” study co-author and University of Bristol paleobiologist Emily Carlisle said in a statement.

Their model estimates the origin of the ages based on when these mammal lineages first appear, and estimates extinction ages based on when the group goes extinct, according to the authors. 

[Related: Mammals’ ears may hold the secret to warm-bloodedness.]

They showed that the groups that include primates, rabbits and hares (Lagomorpha), and dogs and cats (Carnivora) evolved just before the K-Pg mass extinction. This means their ancestors were mingling with dinosaurs.  It was really only after the asteroid impact that the modern lines of today’s placental mammals started to take shape. As with other mammals, they likely began to diversify once the dinosaurs were out of the picture.

These early mammals certainly did thrive. A group of cat-sized mammals called condylarths, which includes the ancestors of today’s hooved animals, lived roughly within the first 328,000 years after the dinosaurs disappeared. Mammals also began to grow significantly since they had less competition for resources. One of the biggest winners among these mammals were Brontotheres or “thunder beasts,” which grew from 40 pound animals roughly the size of coyotes to 2,000 pound goliaths.  

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Living at the extremes of the Triassic era would’ve been pretty rough. It started and finished with massive extinction events, picking up from the end of the single-continent Permian period around 250 million years ago, and giving way to the Jurassic period 50 million years later. The creatures of the Triassic era were a diverse combination of apocalypse survivors, short-lived wonders, and the earliest forms of dinosaurs called the archosaurs. 

One such archosaur was the genus of the Tanystropheus—ancient water-dwelling reptiles with wildly long and skinny necks. First discovered in Germany over 170 years ago, the largest specimens of Tanystropheus had a neck that stretched nearly 10 feet. These strange beasts used their tiny skulls and extensive, inflexible necks to prowl the seas for snacks—some larger species fed on fish and squid while smaller species trawled for soft-shelled animals. Considering such an appendage would probably make for a nightmarish hassle on land, scientists think these creatures spent most of their time wading or swimming in water. 

But new research shows that, perhaps unsurprisingly, these lengthy necks were also gigantic liabilities.

“Paleontologists speculated that these long necks formed an obvious weak spot for predation, as was already vividly depicted almost 200 years ago in a famous painting by Henry de la Beche from 1830,” Stephan Spiekman of the Staatliches Museum für Naturkunde in Stuttgart, Germany said in a release. That painting shows a crocodile-like swimmer chomping on the neck of another dino. “Nevertheless, there was no evidence of decapitation—or any other sort of attack targeting the neck—known from the abundant fossil record of long-necked marine reptiles until our present study on these two specimens of Tanystropheus.”

According to research published by Spiekman and others in the journal Current Biology on June 19, Triassic predators sure knew how to decapitate multiple species of Tanystropheus. Looking closely at two fossils from two distinct species of the aquatic reptile, scientists found clear evidence of snapped necks—including, on one specimen, bite marks right at the snapping point. The skulls and necks of these specimens look more or less well preserved and undisturbed, but the rest of their bodies are nowhere to be found. 

“The fact that the head and neck are so undisturbed suggests that when they reached the place of their final burial, the bones were still covered by soft tissues like muscle and skin,” Eudald Mujal, another study author also from the Stuttgart Museum, said in the release. The predator hadn’t eaten the dinosaur’s face, which Mujal speculates was because the skinny neck and small head wouldn’t have made a meaty meal, unlike other parts of the body. “Taken together, these factors make it most likely that both individuals were decapitated during the hunt and not scavenged,” he added, “although scavenging can never be fully excluded in fossils that are this old.” 

This research just shows how weird evolution can be—after all, long-necked marine reptiles have been successful on Earth for millions of years. Tanystropheus themselves lasted at least 10 million years during an incredibly tumultuous time to be existing on the planet (for reference, the genus Homo has only been around for approximately 3 million years). “In a very broad sense, our research once again shows that evolution is a game of trade-offs,” Spiekman added.

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There are some places in the world that are just magnets for dinosaurs—Utah’s Cedar Mountain Formation, the fossil beds of Liaoning, China, Alberta’s Dinosaur Provincial Park. In the UK, one such hot spot is the Isle of Wight, a 148 square mile island now known as a popular summer holiday spot. Nevertheless, the tiny island is home to numerous dinosaur discoveries, including Europe’s largest prehistoric predator and a tyrannosaurid that lived 60 million years before the iconic Tyrannosaurus rex.  

[Related: Celebrate 30 years of Jurassic Park with these recent dinosaur discoveries.]

However, there’s always something new to discover, even on an island just slightly larger than the city of Atlanta. This time, scientists have uncovered the island’s second armored dinosaur in the Wessex formation which dates back to the earliest years of the Cretaceous. The newly named Vectipelta barretti was described in a study published in the Journal of Systematic Palaeontology on June 15. 

The finding, which utilized fossils that were first uncovered in the 1980s, is particularly important because it reopens the book on the development of ankylosaur dinosaurs in the region. Previously, only one ankylosaur, the Polacanthus foxii, had been found on the entire island. The Polacanthus foxii was first discovered in 1865, and up until now, the Vectipelta barretti had just been lumped in with those fossils. 

“For virtually 142 years, all ankylosaur remains from the Isle of Wight have been assigned to Polacanthus foxii, a famous dinosaur from the island,” Stuart Pond, a researcher at London’s National History Museum department of earth sciences and lead author of the study, said in a statement. “Now all of those finds need to be revisited because we’ve described this new species.” 

The newly described dinosaur has a very different pelvis and distinct neck and back vertebrae compared to the Polacanthus. Additionally, it features unique blade-like and recurved spikes along its back, Susie Maidment, a dinosaur researcher at the National History Museum, said in a statement. In fact, the differences, as well as phylogenetic analysis, lead the authors to believe that the Vectipelta’s closest kin may have hailed all the way from China. 

“And when we put Vectipelta into a big evolutionary analysis to work out the relationship of all these different dinosaurs, we find that Polacanthus and Vectipelta are not actually very closely related,” Maidment said. “They are really quite far apart in terms of ankylosaur evolution, so it is really very clear that this is a different species.”

[Related: Feisty ankylosaurs clubbed each other with their tails.]

During the Early Cretaceus (about 145 to 100 million years ago) when the Vectipelta would’ve roamed free, the continent of Pangea was rifting apart and the climate was much warmer worldwide.  Europe at this point was a series of islands, one of which including today’s southern England and the Isle of Wight. There was little or no ice at either of the poles, and sea levels were around 557 feet higher than they are today. 

While Ankylosaurs were typically plant eaters, similarly to the much beloved Jurassic-era Stegosaurus, they still certainly weren’t to be messed with—those bony, spiky plates were built to fend off carnivorous predators.

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It’s been 30 years since Jurassic Park first roared into movie theaters with its dino DNA, vicious velociraptor attacks, and the cautionary reminder that “life finds a way.” The franchise has incrementally evolved alongside increased knowledge of what dinosaurs actually looked like—namely including some dinosaur feathers in the most recent film—and even inspired one of its young actors to join paleontologists on a dig. Even after centuries of digging and discovery, there are still numerous dino mysteries to uncover.

[Related: The real Jurassic Park may have been in the Arctic.]

In celebration of the film’s 30th birthday, here’s a look at some of the more recent and real-life news in the world of paleontology and dinosaurs.

The face of a changing planet

A newly discovered plant-eating dinosaur named Iani smith may have been the “last gasp” when the Earth’s climate warmed significantly around about 100 million years ago, leading to major changes in dinosaur populations around the world. 

The dinosaur named for the two-faced Roman god of change belonged to a group of dinosaurs called ornithopods. These two-legged grazers eventually gave rise to the duckbill dinosaurs such as Parasaurolophus and Edmontosaurus. The skeleton of a juvenile dinosaur including limbs, vertebrates, and skull was uncovered at Utah’s Cedar Mountain Formation are described in a study published June 7 in the journal PLoS ONE. 

Iani smithi lived in present-day Utah about 99 million years ago during the mid-Cretaceous. The bipedal creature boasts a powerful jaw with teeth that were designed to gnaw through tough plant material. 

[Related: Jeff Goldblum on riding motorcycles—and feeling fear.]

“Iani may be the last surviving member of a lineage of dinosaurs that once thrived here in North America but were eventually supplanted by duckbill dinosaurs,” study co-author and paleontologist at North Carolina State University Lindsay Zanno said in a statement. Zanno is also the head of paleontology at the North Carolina Museum of Natural Sciences.

“Iani was alive during this transition—so this dinosaur really does symbolize a changing planet. This dinosaur stood on the precipice able to look back at the way North American ecosystems were in the past, but close enough to see the future coming like a bullet train. I think we can all relate to that,” Zanno added.

Prehistoric Britain’s semi-aquatic dinosaurs

A team of paleontologists studying a British dinosaur tooth concluded that multiple distinct groups of spinosaurs lived in southern England over 100 million years ago. Spinosaurs are a funny looking group of dinosaurs with crocodile-like skulls that were built for swimming.

In their study published June 1 in the journal PeerJ, a team from the University of Southampton’s EvoPalaeoLab performed a series of tests on a 140 million year old tooth found in a thick rock structure called the Wealden Supergroup in the early 20th century. The Wealden lies across southeastern England and was formed about 140 to 125 million years ago.

“While we can’t formally identify a new species from one tooth, we can say this spinosaur tooth doesn’t match any of the existing species we know about. Given how many individual teeth exist in collections, this could be just the tip of the iceberg and it’s quite possible that Britain may have once teemed with a diverse range of these semi-aquatic, fish-eating dinosaurs,” co-author and paleontologist Neil Gostling said in a statement. 

The study’s results show that distinct and distantly related spinosaur types lived in the region during the Early Cretaceous period.

[Related from PopSci+: Why dinosaurs were terrible swimmers.]

Theropod to bird evolution: “We’ll just have to evolve too.”

Jurassic Park famously delves into the idea that some species of dinosaurs evolved into birds. Scientists are continuing to learn more about the physical changes that some prehistoric animals underwent in their journey to becoming today’s flighty fauna.

A study published June 5 in the journal Nature Ecology & Evolution quantified the evolutionary rate and physical disparities that occurred as some bulky dinosaurs evolved into lighter birds. The team saw a shift to low disparity and a slowed-down evolutionary rate around the time birds originated on the evolutionary tree. This decelerated rate of evolution may be due to a low rate of forelimb evolution.

“We believe that forelimb evolution has been constrained to the basic ‘blueprint’ needed for powered flight, and thus the morphospace that can be realized by early diverging avialans was limited,” study author Wang Min from the Chinese Academy of Sciences said in a statement. 

In addition to these exciting new dinosaur discoveries, reminders of the film’s science continue through some funky virgin births in sharks and crocodiles, advances in CRISPR gene editing, and continued interest in bringing extinct species back to life. 

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On this fossil Friday, we’d like you to meet the rhynchosaur. This ancient reptile is a distant relative of crocodiles and modern birds, roaming through present day North and South America, Europe, Africa, Madagascar, and India between 250 to 225 million years ago. It belongs to a group of roughly sheep-sized ancient reptiles that thrived during the Triassic Period. The Triassic is known for its hot climate and abundance of vegetation.

[Related: This tiger-sized, saber-toothed, rhino-skinned predator thrived before the ‘Great Dying.’]

A study published June 8 in the journal Palaeontology describes a handful of rhynchosaur specimens  found in Devon in southwestern England. Researchers used CT scanning to see how their teeth wore down as the herbivores fed on leafy greens and other rough vegetation, as well as how new teeth were added towards the back tooth rows when the animals grew in size. As the vegetation took its toll on the rhynchosaur’s teeth, they likely starved to death as they aged.  

“Comparing the sequence of fossils through their lifetime, we could see that as the animals aged, the area of the jaws under wear at any time moved backwards relative to the front of the skull, bringing new teeth and new bone into wear,” co-author and University of Bristol paleobiology student Thitiwoot Sethapanichsakul said in a statement. “They were clearly eating really tough food such as ferns, that wore the teeth down to the bone of the jaw, meaning that they were basically chopping their meals by a mix of teeth and bone.”

During the Triassic, rhynchosaurs were an important part of Earth’s ecosystem. Life on Earth was recovering from the greatest mass extinction in the planet’s history. During the Permian-Triassic mass extinction, or the “Great Dying,” massive volcanic eruptions triggered catastrophic climate changes that killed 80 to 90 percent of species on Earth. It paved the way for dinosaurs to dominate Earth, but was even more dramatic than the extinction event that wiped out the dinosaurs 65 million years ago. 

Rhynchosaurs helped set the scene for new types of ecologies as dinosaurs became dominant, followed by the rise of the mammals. 

“I first studied the rhynchosaurs years ago and I was amazed to find that in many cases they dominated their ecosystems,” co-author and University of Bristol paleontologist Mike Benton said in a statement. “If you found one fossil, you found hundreds. They were the sheep or antelopes of their day, and yet they had specialized dental systems that were apparently adapted for dealing with masses of tough plant food.”

[Related: These tiny ‘dragons’ flew through the trees of Madagascar 200 million years ago.]

The team compared examples of earlier rhynchosaurs like the ones unearthed in Devon, with later-occurring samples from Argentina and Scotland. They were able to see how their teeth developed over time, and eventually how this unique dentistry allowed the species to diversify twice. Their chompers changed in the Middle and Late Triassic. 
Ultimately, another period of climate change and especially major changes in the kinds of plants available for the reptiles to eat, allowed the dinosaurs to take over and the rhynchosaurs went extinct just before the end of the Triassic period, roughly 237 to 227 million years ago.

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The fictional and deadly Jurassic Park has nothing on the real-life Dinosaur Cove on the southern tip of Victoria, Australia. Using bones from the fossil-filled hotspot, a team of paleontologists have confirmed that pterosaurs—more commonly known as pterodactyls—flew over Australian skies as far back as 107 million years ago. Their findings are detailed in a study published May 31 in the journal History Biology.

[Related: This pterosaur ancestor was a tiny, flightless dog-like dinosaur.]

The team examined two pieces of prehistoric bone that were extracted from Dinosaur Cove over 30 years ago. The bones belonged to two different pterosaurs, and were examined by experts from Curtin University in Perth and Melbourne’s Museums Victoria. A partial pelvis bone belonged to a pterosaur with a wingspan over 6.5 feet, and the smaller wing bone belonged to a juvenile pterosaur. These bones turned out to be the oldest remains of the giant winged reptiles ever recovered in Australia, which is better known for its larger sauropod fossils. 

Closely related to dinosaurs, pterosaurs soared through the skies during the Mesozoic Era, about 252 million years ago.

“During the Cretaceous Period (145–66 million years ago), Australia was further south than it is today, and the state of Victoria was within the polar circle—covered in darkness for weeks on end during the winter. Despite these seasonally harsh conditions, it is clear that pterosaurs found a way to survive and thrive,” study co-author and Curtin University PhD student Adele Pentland said in a statement. 

According to Pentland, remains of pterosaurs are a rare find worldwide. Even fewer remains have been discovered at regions that were once high paleolatitude locations, including Victoria. She told CNN that less than 25 sets of pterosaur remains from four species have been found in Australia since the 1980s, compared to more than 100 sets in countries like Argentina and Brazil.  

“So these bones give us a better idea as to where pterosaurs lived and how big they were. By analyzing these bones, we have also been able to confirm the existence of the first ever Australian juvenile pterosaur, which resided in the Victorian forests around 107 million years ago,” said Pentland.

[Related: The biggest animal ever to fly was a reptile with a giraffe-like neck.]

The specimens were found in the 1980s in a Dinosaur Cove expedition led by paleontologists Tom Rich and Pat Vickers-Rich. Their discovery of big-eyed dinosaurs along this area of coastline helped spark a major shift in how dinosaurs were more generally perceived. These “dinosaurs of darkness” gave paleontologists a glimpse of survival without sunlight and reframed questions about whether dinosaurs were warm-blooded creatures. 

“These two fossils were the outcome of a labor-intensive effort by more than 100 volunteers over a decade,” Tom Rich said in a statement. “That effort involved excavating more than 60 meters [196 feet] of tunnel where the two fossils were found in a seaside cliff at Dinosaur Cove.”

The biggest pterosaur scientists know of so far is Quetzalcoatlus northropi, which was found in Texas. Since everything is bigger in Texas, this pterosaur had a wingspan of about 32 to 36 feet. Australia’s largest pterosaur is the Thapunngaka shawi. It was discovered in 2021 by a team from the University of Queensland and boasts a wingspan of roughly 22 feet. 

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A dinosaur specimen unearthed in Castellón, Spain in 2011 is likely a brand new species and genus of spinosaur, a family of dinosaurs whose fossils have been found in Europe, Asia, South America, and Asia. The new findings were published May 18 in the journal Scientific Reports. 

[Related: What was going on inside of this spinosaur’s brain?]

This new species is named Protathlitis cinctorrensis—which comes from the Greek word for “champion” in reference to football club Villarreal C.F. ‘s Europa League win in 2021.

“Three of the authors of this paper live in Villarreal, and with the club’s centenary this year, we wanted to recognise its work both on and off the pitch by naming a dinosaur genus after it,” co-author and Jaume I University paleontologist Andrés Santos‑Cubedo, said in a statement. 

The discovery, alongside another the uncovering of a moderately sized dinosaur named Vallibonavenatrix cani, suggests that the Iberian peninsula  could have been a very diverse area for medium-to-large bodied spinosaurid dinosaurs. 

Spinosaurs were carnivorous theropod dinosaurs that were typically large and stood on two feet. Some of the better known spinosaurids include the crocodile-mouthed 4,000 pound Baryonyx and Spinosaurus, who might be recognizable from its fictional fight with Tyrannosaurus in Jurassic Park III. Many of these unusual 13 to 22 ton dinos stalked ancient riverbanks preying on large fish and lived a different lifestyle than more familiar theropods, such as Allosaurus and Tyrannosaurus.

“The spinosaurs are quite special theropods. They ate fish and lived in and around water, but there’s a lot of debate about just how aquatic they were,” Cassius Morrison, a co-author of the study and PhD student from the UK’s Natural History Museum, said in a statement. “Some scientists suggest they were like herons, snapping up fish while wading, while others think they were more like a penguin, and could move underwater to hunt fish. Suchomimus seems to be more like a heron, while Baryonyx and Spinosaurus had higher bone density which might mean they could have spent time underwater.”

Spinosaurs are believed to have originated in Europe before moving to Africa and Asia sometime during the Late Cretaceous, but the evidence of their existence in present-day Spain is primarily based on fossilized tooth remains.  

In this study, a team of paleontologists analyzed a right jaw bone, one tooth, and five vertebraediscovered in the Arcillas de Morella Formation in eastern Spain. This formation is known for containing fossils of Iguanodon and its relatives and titanosaur-like dinosaurs.

[Related: Spinosaurus bones hint that the spiny dinosaurs enjoyed water sports.]

The fragments were dated to between 127 and 126 million years ago, during the late Barremian or Early Cretaceous period. The team estimates that the new specimen was around 32 to 36 feet long—about the length of a telephone pole.  

The team compared this newly-named specimen to data on other spinosaurs to figure out its evolutionary relationship to other species within the family of dinosaurs. They believe that this new dinosaur appeared in the Early Cretaceous in a large area of land in the Northern hemisphere called Laurasia. 

“Our research demonstrates that two subfamilies of spinosaur occupied western Europe during the Early Cretaceous (145-100 million years ago) before later migrating to Africa and Asia,” Andrés said. “Baryonyx-like spinosaurs became dominant in Europe, while Spinosaurus-like spinosaurs were most abundant in Africa.”

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Dinosaur Mysteries digs into the secretive side of the “terrible lizards” and all the questions that keep paleontologists up at night.

WE ARE IN THE MIDDLE of history’s greatest fossil rush. Forget about the 19^th-century Bone Wars or the early 20^th-century rise of US museums—paleontologists today are finding more dinosaurs faster than before. On average, they name a new nonavian dinosaur species every two weeks. Some of this year’s fresh arrivals include the long-necked herbivore Chucarosaurus, the duckbill Malefica, and the dome-headed Platytholus.

Despite this incredible rate of discovery, however, plenty of dinosaurs are missing from the paleontological history we’re trying to piece together.

If dinosaur seekers had their druthers, Earth’s geology would look something like an onion. Experts would work through perfectly stacked layers of sedimentary rock that contain comprehensive records of all the species that lived in ancient habitats through time. But such good fortune has eluded scientists. Since the 1800s, geologists and paleontologists have recognized that the fossil record is uneven and sporadic, made up of sediment that accumulated in environments such as streams, oceans, and dune-covered deserts. Most living things were eaten or decayed long before they could become fossilized.

Circumstances have to be just right for a fossil to form. The most ideal settings include relatively wet lowlands where rivers, streams, and other flowing waters could carry the requisite sand and silt to cover bodies. The blanket of sediment helped keep fossils-to-be from being nibbled on by scavengers or destroyed by the elements. As sediment turned to stone, mineral-laden water trickled through the encased body and replaced bone and sometimes soft tissues in a process called permineralization. The nature of the reaction varied from case to case, affected by everything from the size of the dinosaur to the local environment. This explains why we find some prehistoric creatures as partial, jumbled skeletons and others as delicately preserved fossils surrounded by feathers with not a bone out of place. 

In the end, paleontologists need to work with a fraction of a fraction of life’s story. Even some of the best fossil-hunting spots in the world are far from perfect. Consider the gorgeous banded rock layers of Dinosaur Provincial Park in Alberta, Canada, a hotspot for the discovery of stunning Late Cretaceous species such as the crested duckbill Lambeosaurus and the toothy tyrannosaur Gorgosaurus. In a 2013 review of fossils discovered in the park, paleontologists found that dinosaurs that weighed more than 130 pounds are often found at about 78 percent completeness while those below 130 pounds are usually found at about 7.6 percent completeness. (Paleontologists can often differentiate species even from such limited remains based on subtle anatomical traits that experts catalog over time.) Evidently, ancient ecosystems were much harsher on small specimens, masking how numerous they were in thriving times.

The fossil record runs rampant with sampling biases as well. Paleontologists come into the field with their own ideas of what to look for, and many are motivated to study megafauna, which hold more public allure and pose less of a challenge to excavate. A little more than a century ago, when paleontologists were beginning to search Alberta’s 75-million-year-old rocks, the big dinosaurs were much easier to find. Museums—both in the province and in faraway cities like New York—were hungry for near-complete, showstopping reptiles to lure in visitors. No surprise then that the same 2013 assessment from Dinosaur Provincial Park found it took paleontologists an average of 33.6 years to discover and name species above the 130-pound threshold and 65.9 years for those below.

The pattern holds for other dinosaur-bearing rocks, like the famous multistate Hell Creek Formation that preserves the last days of the dinosaurs in western North America. Even though paleontologists have named small dinosaurs when they’ve happened across their fossils, experts have been actively considering the more diminutive reptiles only in the past decade or so.

Of course, it’s a wonder that we know about any dinosaurs at all. Every single fossilized skeleton or footprint has beaten long odds to tell us about ecosystems that we’ll never get to experience directly. Details of how these ancient habitats changed are critical to debates on whether dinosaurs were flourishing or struggling as the great Age of Dinosaurs approached its closing act 66 million years ago.

For example, paleontologists used to wonder why there seemed to be far more dinosaur species roaming western North America 75 million years ago than 66 million years ago, just prior to the K/Pg extinction that decimated them. Some experts reasoned that the creatures were already in decline. But when researchers looked at how prehistoric habitats shifted during that 9-million-year window, they found that environments better at preserving fossils diminished over time. A warm, shallow sea that divided North America drained off the continent, taking with it the wet, marshy lowlands that immortalized dinosaurs so extensively. So there were probably more dinosaur species running around the continent 66 million years ago than we’ll ever know about, a gap created by changes to the land itself.

So where would these missing fauna have dwelled? There’s every reason to think that dinosaurs clambered around ancient mountain ranges—but mountains are hotspots of erosion, not deposition, so the accumulations of sediment needed to preserve dinosaur bodies weren’t present there. The erosion problem also applies to some deserts, like the one in modern-day Arches National Park. Even though it’s perfectly natural to think of dinosaurs wandering between the expanses of bright sandstone, these landscapes were too dry and disintegrated for dinosaurs to be buried and fossilized in them.

It’s also entirely possible that some “rare” species in well-documented fossil beds were transported there by the elements after death. Think of the heavily armored ankylosaurs that were swept out to burials at sea, or the long-necked sauropods that dwelled in the hills but are known by the bones washed into cave systems, where they were buried. Fossil beds often represent where organisms became preserved, not necessarily where they lived.

Because the Earth is not an onion, much of the fossil record remains uneven and unexposed. While somewhat dated now, one 2006 estimate proposed that more than 70 percent of discoverable dinosaur species are still hidden beyond detection.

Much of what we’ve learned about the dinosaur story comes from the later parts of the Triassic, Jurassic, and Cretaceous. We have way less information on the middle of each Mesozoic period, times when new dinosaur dynasties were forming and the ecosystems they thrived in were evolving with them. When experts uncover these animals, they enrich our knowledge of these mysterious times in dinosaur history. In 2019, for example, paleontologists described the sharp-toothed Asfaltovenator from the Middle Jurassic in Argentina. The species offers some context for the rise of the world’s first truly giant carnivores, like Allosaurus. It’s in these middle chapters that we stand to learn the most—to learn about the dinosaurs that are most likely to change and challenge what we think we know about a world millions of years ago.

We hope you enjoyed Riley Black’s column, Dinosaur Mysteries. Check back on PopSci+ in June for the next article.

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A recent discovery sounds like the beginning of another Jurassic Park reboot—but this time beetles are taking center stage instead of mosquitoes. These new fossils preserved in amber show evidence that beetles fed on dinosaurs about 105 million years ago, according to a study published April 17 in the journal Proceedings of the National Academy of Sciences (PNAS).

[Related: Entombed in amber, this tiny crab hails from the age of dinosaurs.]

The most impressive and complete specimen was found in the amber deposit of Rábago/El Soplao in northern Spain. The amber contains shedded fragments–or molts–of small beetle larvae tightly surrounded by some pieces of downy feathers. The feathers once belonged to an unknown theropod dinosaur that was either avian or non-avian. Theropods that flew and those that were more Earth-bound typically shared indistinguishable feather types during the Early Cretaceous period. According to the team, the feathers do not belong to modern birds, since that group of animals appeared roughly 30 million years later during the Late Cretaceous. 

On Earth today, vertebrates and arthropods, like today’s ticks and lice, have a complex ecological relationship that has likely coexisted for more than 500 million years. The interactions between the two are believed to have shaped both vertebrate and arthropod evolutionary history, but evidence of arthropod-vertebrate relationships is still extremely rare in the fossil record, according to the team on this study. 

They found that the larval molts preserved in this study were related to modern skin beetles, or dermestids. These beetles feed on organic materials that decay over time, sometimes bothering dried museum specimens tucked away in closets. However, dermestids do play a key role in recycling organic matter, commonly living in birds nests and in places on mammals where hair, skin, or feathers accumulate.

The authors found that some of the feather portions and other remains were in intimate contact with the molts of the dermestid beetles and have some evidence of damage or decay. 

“This is hard evidence that the fossil beetles almost certainly fed on the feathers and that these were detached from its host,” study co-author and Geological and Mining Institute of Spain of the Spanish National Research Council geologist Enrique Peñalver said in a statement. “The beetle larvae lived—feeding, defecating, molting—in accumulated feathers on or close to a resin-producing tree, probably in a nest setting. A flow of resin serendipitously captured that association and preserved it for millions of years.” 

[Related: These beetles sniff out fungus-infected trees to find their next target.]

It is still unclear if the feathered theropod host benefited from the beetle larvae feeding on detached feathers and that it could have occurred in a nest setting, where the host was sitting on eggs.  

“However, the theropod was most likely unharmed by the activity of the larvae since our data show these did not feed on living plumage and lacked defensive structures which among modern dermestids can irritate the skin of nest hosts, even killing them,” co-author and paleobiologist from Oxford University Museum of Natural History Ricardo Pérez-de la Fuente said in a statement.

Three other pieces of amber that had isolated beetle molt that were in a different stage of the beetle life cycle were also studied, which allowed better understanding of the role that their feathery diet played.

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A dinosaur skull found in Queensland, Australia has the exciting honor of being dubbed Australia’s first nearly complete sauropod skull. 

Research published April 12 in the journal  Royal Society Open Science describes the 19.6 inch long skull, and details that the find was from a species Diamantinasaurus matildae (D. matildae). Diamantinasaurus is a member of the group Sauropoda, which also includes the more famous Brachiosaurus and Brontosaurus and are known for small heads, long necks and tails, and barrel-like bodies.  

[Related: Cushy feet supported sauropods’ gigantic bodies.]

The dinosaur, nicknamed ‘Ann,’ was discovered by the Australian Age of Dinosaurs Museum in 2018 near Winston in central Queensland. Ann is the third fossil specimen of D. matildae to have been discovered by this museum, and the fourth specimen overall. It lived in Australia over 100 million years ago and fell under the titanosaur group– a category of sauropods that included the largest animals to live on land in Earth’s history. D. matildae was a middle size sauropod, with the largest members reaching close to 131 feet long and over 170,000 pounds. Sauropods were also herbivores, subsisting entirely on a diet of plants. 

The team on this study said that it is rare to find a sauropod skull at all, especially one so well-preserved. It is only the fourth specimen of D. matildae ever found and the analysis of this first nearly complete skull is helping scientists learn more about the animal’s feeding habits, relationship to other sauropod dinosaurs, and physical anatomy. According to the team, Ann is not only the first sauropod dinosaur found in Australia that includes most of the skull, it also is the first Diamantinasaurus specimen to preserve a back foot.

“In analyzing the remains, we found similarities between the ‘Ann’ skull and the skull of a titanosaur called Sarmientosaurus musacchioi, which lived in South America at about the same time as Diamantinasaurus lived in Queensland. These include details of the braincase, the bones forming the back end of the skull near the jaw joint, and in the shape of the teeth (which are conical and curved),” co-author and Curtin University paleontologist Stephen Poropat said in a statement. 

[Related: This dinosaur’s record-breaking neck defies the laws of nature.]

According to Poropat, the findings support earlier theories that suggests sauropods used Antarctica as a pathway between Australia and South America during the mid-Cretaceous period–between 100 and 95 million years ago.

“Warmer conditions that far south might have been favorable for them. The window between 100 and 95 million years ago was one of the warmest in Earth’s geologically recent history, meaning that Antarctica, which was more or less where it is now, had no ice,” Poropat said. “Similarly, Australia, which was much further south than today, was warmer with less seasonality. In that climate, Antarctica was forested, and might have been an attractive habitat or pathway for wandering sauropods.”

The study suggests that Diamantinasaurus was one of the most ‘primitive’ or not as evolved titanosaurs. Learning more about this species of giant dino might explain why they were so successful until the dinosaurs’ mass extinction.  

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Watching a bird leap around on its crooked legs before it takes off into the air is kind of  like turning back the evolutionary clock and watching a theropod dinosaur. Numerous paleontologists believe that theropod group, which includes the spinosaurus, tyrannosaurus rex, and velociraptor, evolved into the birds we see on Earth today. This would make them the only dino-descendants that survived catastrophic extinction 66 million years ago.

Like birds, theropod dinos also laid eggs, and scientists are beginning to fill in evolutionary gaps by studying the shelly remains. A study published April 3 in the journal Proceedings of the National Academy of Sciences (PNAS) examined the calcium carbonate left behind in the eggs of a funky theropod called Troodon and found that the dinosaurs laid four to six eggs in communal nests. 

[Related: Newly found titanosaur eggs reveal dino nurseries once teemed with baby giants.]

Troodon was a carnivorous dinosaur over six feet long that lived in North America about 75 million years ago. It had some bird-like features, particularly its light and hollow bones, two legs, and fully developed feathery wings. However, the dinosaur’s relatively large size kept it from flying, but it likely ran very fast and caught prey in strong claws. 

Troodon females also laid eggs that are more similar in shape to the asymmetric eggs laid by  modern birds than to the round reptile eggs. Their eggs were blue-green colored like other theropod eggs, and they have been found half buried into the ground. The international team of scientists on this study believes that mother Troodons sat and brooded on them.

To learn more, the team examined the calcium carbonate left behind in some well-preserved Troodon eggshells. They used a method developed in 2019 called “dual clumped isotope thermometry.” 

With this technique, they could measure the extent to which heavier isotopes of oxygen and carbon clump together in carbonate minerals. Isotopic clumping is temperature-dependent, and the prevalence of this clumping helped the team determine the temperature at which the carbonates crystallized. The eggshells were likely produced at temperatures of 107 degrees Fahrenheit and then deduced down to 86 degrees, which is very similar to modern birds. 

[Related: A fossilized egg laid by an extinct, human-sized turtle holds a rare jackpot.]

The team then compared  the isotopic compositions of reptile egg shells (alligator, crocodile, and multiple turtle species) with modern birds (chicken, sparrow, wren, emu, kiwi, cassowary, and ostrich) to see if Troodon was closer to either birds or reptiles. Two different isotopic patterns were revealed. The reptile eggshells have isotopic compositions matching the temperature of the surrounding environment, since they are cold-blooded and form their eggs slowly. Birds leave a recognizable non-thermal signature in the isotopic composition, which is evidence of quick eggshell formation. 

“We think this very high production rate is connected to the fact that birds, unlike reptiles, have a single ovary. Since they can produce just one egg at the time, birds have to do it more rapidly,” study author and geochemist from Goethe University Frankfurt in Germany Mattia Tagliavento said in a statement. 

The team compared these results to the remains of Troodon eggshells and did not not detect the isotopic composition which is typical for birds. According to Tagliavento,  “this demonstrates that Troodon formed its eggs in a way more comparable to modern reptiles, and it implies that its reproductive system was still constituted of two ovaries.”

As a last step, the researchers combined their results with existing knowledge about body and eggshell weight and determined that Troodon only produced only four to six eggs per reproductive phase. They found this observation particularly notable because Troodon nests are typically large and have up to 24 eggs, so the team believes that this means they laid their eggs in communal nests. This communal egg nesting behavior is seen in modern day ostriches.  

“Originally, we developed the dual clumped isotope method to accurately reconstruct Earth’s surface temperatures of past geological eras,” study co-author, geochemist, and developer of the new thermometry method Jens Fiebig, said in a statement. “This study demonstrates that our method is not limited to temperature reconstruction, it also presents the opportunity to study how carbonate biomineralization evolved throughout Earth’s history.”

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Real predatory dinosaurs like the infamous Tyrannosaurus rex may have looked quite a bit different than their movie star counterparts—and not just because they had feathers. Theropods like the T. rex may have also had completely different mouths. Instead of a lipless grin and permanently exposed teeth with their upper jaw hanging over the lower jaw like a crocodile, the T. rex may have boasted scaly lips covering up their teeth.

The details of this possible oral makeover are described in a new study published March 30 in the journal Science. An international team of researchers say that these lips were more similar to lizards and their relative, the tuatara. The tuatara, the last survivors of an order of reptiles that thrived during the age of the dinosaurs, is a rare reptile that is found only in New Zealand that can live up to 100 years.

[Related: What are dinosaur feathers like?]

The team examined the tooth structure, wear patterns, and jaw morphology of reptiles from both lipped and lipless groups. They found that the theropod mouth functionality and anatomy actually resembled lizards more than crocodiles. The study says this similarity implies the T. rex had lizard-like oral tissues, with scaly lips covering up their teeth.   

“Paleontologists often like to compare extinct animals to their closest living relatives, but in the case of dinosaurs, their closest relatives have been evolutionarily distinct for hundreds of millions of years and today are incredibly specialized,” study co-author and Canada’s Royal BC Museum paleontology collections manager and researcher Derek Larson, said a statement. “It’s quite remarkable how similar theropod teeth are to monitor lizards. From the smallest dwarf monitor to the Komodo dragon, the teeth function in much the same way. So, monitors can be compared quite favorably with extinct animals like theropod dinosaurs based on this similarity of function, even though they are not closely related.”

Additionally, therapod lips were likely not muscular, as seen in mammals. Most reptiles have lips that cover up teeth, but can’t be moved independently. Humans and mammals can make all sorts of movements with their lips, like curling them into a snarl or posing with “duck face” in a selfie, but reptile lips can’t. 

The study also found that the tooth wear in lipless animals was different from what has been seen in carnivorous dinosaurs. Dinosaurs also had teeth that were no larger than modern lizard teeth when compared to their relative skull size. The teeth were likely not too big to be covered up by scaly lips. 

[Related: Is T. rex really three royal species? Paleontologists cast doubt over new claims.]

Another more lizard-like feature in theropods was the distribution of small holes around the jaws that supply blood and nerves to dinosaur gums and tissues in the mouth. When modeling mouth closure in lipless theropod jaws, the team found that the lower jaw either had to crush jaw-supporting bones or disarticulate the jaw joint to seal the mouth.

“As any dentist will tell you, saliva is important for maintaining the health of your teeth. Teeth that are not covered by lips risk drying out and can be subject to more damage during feeding or fighting, as we see in crocodiles, but not in dinosaurs,” said co-author Kirstin Brink, a vertebrate paleontologist at the University of Manitoba, in a statement.

According to the team, this prehistoric lip debate has roots all the way back to the nineteenth century, when scientists began restoring dinosaur fossils. It became more prominent when blockbuster films like Jurassic Park and documentaries took to the screen and have since become deeply rooted in popular culture. 

“Curiously, there was never a dedicated study or discovery instigating this change and, to a large extent, it probably reflected preference for a new, ferocious-looking aesthetic rather than a shift in scientific thinking,” paleontologist and co-author Mark Witton from the University of Portsmouth, said in a statement. “We’re upending this popular depiction by covering their teeth with lizard-like lips. This means a lot of our favorite dinosaur depictions are incorrect, including the iconic Jurassic Park T. rex.”

This study provides new insights into how paleontologists can reconstruct both the soft tissues and appearance of extinct species, so that scientists can learn more about how they fed, maintained their tooth health, and even more broad patterns in their evolution. 

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Dinosaur Mysteries digs into the secretive side of the “terrible lizards” and all the questions that keep paleontologists up at night.

DINOSAURS DOMINATED EARTH. We all know the trope. The stupendous reptiles were so numerous and unique that they claimed a 150-million-year-long chunk of Earth’s history as the Age of Dinosaurs. 

But talking about a single group of organisms “dominating” the planet is silly. For one thing, the only dinosaurs bobbing in the ocean waves were carcasses, washed out by coastal storms.

Oceans have covered the vast majority of our planet for billions of years and contain more than 96 percent of Earth’s water at present. Dinosaurs, so far as we can tell, never made the sea their home. And paleontologists still don’t know why.

If there’s anything more challenging than understanding why a species evolved a particular way, it’s trying to backtrack on the evolutionary roads it didn’t take. Nature is full of invisible barriers and bottlenecks that open and close based on previous change. We usually don’t perceive these biological constraints until we run into a “Why not?” question. And even then, it can be difficult to distinguish between what’s actually impossible and what simply didn’t happen due to coincidence. In the case of the dinosaurs, though, we have a few clues as to why the seas remained beyond their domain.

For the most part, dinosaurs were atrocious swimmers. But it took decades for paleontologists to figure this out as they waited for the right fossil tracks, analyses of dinosaur bone structure, and computer methods capable of estimating the buoyancy of dinosaurs. During much of the 20th century, when experts insulted living reptiles and dinosaurs alike by characterizing the extinct saurians as dimwitted slowpokes, some paleontologists thought long-necked sauropods like Brachiosaurus could only support their weight in water. They also posited that the “duck-billed” dinosaurs, or hadrosaurids, plunged into lakes when tyrannosaurs stalked too near—the only defense herbivores that weren’t covered in armor or horns could have, apparently. Starting in the 1970s, paleontologists realized that fossilized tracks and other clues about the sauropods and duck-bills indicated they lived in terrestrial environments and weren’t adept in water. Not only that, but the relatively few trace fossils made by swimming dinosaurs—scrapes in the sediment from when they kicked their feet—were created by carnivorous dinosaurs, undercutting the idea that water was a refuge for plant eaters. 

A key dinosaurian trait may have prevented the reptiles from getting cozy in the water. The bony respiratory systems of sauropods and theropods show evidence of a unique set of air sacs connected to the lungs and other parts of the respiratory system. These soft-tissue pockets allowed the creatures to breathe more efficiently than mammals by keeping new air constantly flowing instead of relying on distinct inhales and exhales. (Birds have the same feature, with the added benefit that it keeps their skeletons light by filling bony spaces with air.) But when modeling how these air pockets would have affected dinosaurs’ swimming ability, paleontologists found that even large species would have acted like inflatable pool toys—too light for their size to be stable in the water. Adaptations to a life aquatic usually involve denser bones as a form of natural ballast—too much internal air would make dinosaurs work too hard to stay submerged. So much like us, while some dinosaurs could swim, they certainly weren’t diving neck and neck with the prehistoric sea turtles and plesiosaurs.

The same problem comes up for dinosaurs that were once considered skilled swimmers. The sail-backed, roughly 50-foot-long Spinosaurus has a few anatomical hallmarks associated with dipping and diving: Some of its bones seem extra dense, like those of other semiaquatic animals, and its tail is long and eel-esque, like a giant hitched-on paddle. But recent studies have found that Spinosaurus’ airy skeletal structure would have made it unstable in water too, and that the huge sail would have hampered the dinosaur’s ability to chase after prey while submerged. It’s more likely that the creature, once heralded as the world’s first swimming dinosaur, was more of a wader that plodded through the shallows as it tried to ambush fish. While additional evidence might alter the picture, especially because no one has found anything close to a complete Spinosaurus skeleton, for now the dinosaur most closely associated with the water was less aquatic than an alligator.

In all, after more than two centuries of searching, paleontologists have not identified a single dinosaur fossil that definitely spent most of its life at sea. The few specimens dug up from marine sediments—like the beautifully preserved armored Borealopelta from Alberta—represent dinosaurs that perished inland or along the coasts and were washed out to sea by storms or local flooding. Some became food for sharks and marine reptiles; some formed temporary reefs; and some quickly got buried under rock and soil, preserving their scales in place. But there were plenty of other reptiles in the sea—fish-like ichthyosaurs, long-necked plesiosaurs, and mosasaurs that were the ocean equivalent of Komodo dragons—that prove the dominion of dinosaurs was exaggerated. 

Of course, we know that dinosaurs eventually did wander into the water. For example, about 5 million years after the asteroid impact that ended the Cretaceous, the first ancestors of penguins took the plunge. Today, these water-savvy birds “fly” by flapping their wings underwater and sport a variety of adaptations, from hydrophobic feathers to salt-excreting vessels in their bills, that allow them to spend a great deal of their time in the ocean. But they still reproduce on land, shedding yet another clue to why extinct dinosaurs never hit the deep blue.

So far as we know, all dinosaurs laid eggs—from the very first terrible lizard (“dinosaur” translated into Greek) 243 million years ago to the chickadees bouncing around on the sidewalk in the present. Whereas other marine reptiles repeatedly evolved ways to give birth, likely starting with the soft-shelled eggs that some snakes and lizards retain today, dinosaurs don’t seem to have ever evolved a different capability. Or perhaps they did but were so late to the party that the seas were already full of nimble, sharp-toothed reptiles ready to munch on any awkward dino-paddlers. The ancient world of the dinosaurs was one that ended at the shoreline, leaving plenty of space for other creatures to rule the water.

We hope you enjoyed Riley Black’s column, Dinosaur Mysteries. Check back on PopSci+ in May for the next article.

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Over 60,000 years ago, an eagle relative with an almost 10 foot wingspan stalked the skies over southern Australia. Dynatoaetus gaffae (Gaff’s powerful eagle) had talons that could even snatch a koala or small kangaroo for dinner. The massive bird of prey was likely the largest continental eagle the world had ever seen. 

A study published March 16 in the Journal of Ornithology details how a team of fossil hunters from Flinders University in Australia put together this bird’s story. Four large fossilized bones were collected in Mairs Cave southern Australia’s Flinders Ranges  as far back as 1956 and 1969. The authors found an additional 28 bones scattered among the boulders in the site whoch helped them create a better picture of this giant extinct bird. 

[Related: This dragon-like reptile once soared over Australia.]

This now extinct raptor is closely related to Old World vultures that prowled Africa and Asia during the Pleistocene. In today’s fauna, its closest relative is likely the critically endangered monkey-munching Philippine Eagle. During the late Pleistocene Epoch, when giant megafauna like the mammoth roamed the Earth and ice sheets and glaciers were growing, Dynatoaetuswas likely the top avian predator on the planet. 

“It’s often been noted how few large land predators Australia had back then, so Dynatoaetus helps fill that gap,” said study author and Flinders University paleontologist Ellen Mather, in a statement.  “This discovery reveals that this incredible family of birds was once much more diverse in Australia, and that raptors were also impacted by the mass extinction that wiped out most of Australia’s megafauna.”

Dynatoaetus and another recently described smaller bird named Cryptogyps represent a new genera of raptors that are unique to Australia. 

“[Dynatoaetus] was humongous. Larger than any other eagle from other continents, and almost as large as the world’s largest eagles once found on the islands of New Zealand and Cuba, including the whopping extinct 13kg [28 pound] Haast’s eagle of New Zealand,” said Trevor Worthy, a study co-author and paleontologist at Flinders University, in a statement. 

[Related: Giant wombats the size of small cars once roamed Australia.]

Dynatoaetus also coexisted with the Wedge-tailed Eagle, a species that currently lives in Australia. The team says that this has interesting implications.

“Given that the Australian birds of prey used to be more diverse, it could mean that the Wedge-tailed Eagle in the past was more limited in where it lived and what it ate,” said Mather. “Otherwise, it would have been directly competing against the giant Dynatoaetus for those resources.”

Most of Australia’s eagles and vultures like the Dynatoaetus went extinct about 50,000 years ago, along with most of the continents’s megafauna.  One 2020 study found that a possible explanation is extreme environmental change and deterioration (loss of water, increased burning of trees and grass, etc.) that wiped out at least 13 super-sized megafauna species, including the world’s largest wombats and kangaroos.

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Dinosaurs came in all shapes and sizes, but we know they could get pretty darn big. For sauropods, a clade of dinos that roamed the planet from the Early Jurassic all the way to the Cretaceous–Paleogene extinction event, their size was largely reflected in their long necks. But according to new findings, the Mamenchisaurus sinocanadorum uncovered in modern-day China may have been the longest-necked of them all.

In a study published today in The Journal of Systematic Paleontology, an international team of scientists determined that this particular specimen of sauropod had a 49-foot-long neck—that’s six times as long as a giraffe neck. 

“It would require a lot of muscles to hold up a neck that size, and then there’s the question of how it gets air down to the lungs and back up again,” Paul Barrett, a professor at the Natural History Museum in London, said in a press release. “This could support the theory that these necks were a sexually selected feature where only the strongest and fittest dinosaurs that were able to hold up these giant necks in impressive displays were able to mate.” 

[Related: Feisty ankylosaurs clubbed each other with their tails.]

This took paleontologists quite a bit of puzzling—there’s only one Mamenchisaurus sinocanadorum specimen to analyze, discovered in 1987 at a site in the Shishugou Formation in northwestern China. The skeleton only includes the front end of the neck, a rib, some skull bones, and a lower jaw. 

So, how do you measure the entire length of a neck from just a few bones? Well, you have to find a similar species to compare it to. In 2012, the giant sauropod Xinjiangtitan was uncovered in China with an intact 43-foot-long neck. Using an “elementary bit of maths,” Barrett explained, the team was able to look at proportions of the relative’s vertebrae and scale up the incomplete skeleton. What they found was a specimen that could very well be a record-breaker. 

But the team didn’t just figure out how long the dinosaur’s neck was—they prodded at the biomechanics of how such a body part could even exist. Using computer-tomography scanning, the authors found that the hollow vertebrae of the massive sauropod was around 69- to 77-percent air, which is similar to modern-day storks. The authors determined that to protect such a lightweight neck from getting hurt, the dinosaur had 13-foot-long rod-like cervical ribs on either side for stability. 

“Biomechanical studies of the [Mamenchisaurus] neck suggest that it was elevated at only a relatively shallow angle above the horizontal (20 to 30°). However, even at this relatively shallow angle, the extreme length of the neck would still mean that the animal’s head could reach heights of around [25 to 33 feet] above ground level,” co-author Paul Upchurch, a professor of palaeobiology from the University College London, said in a press release. 

[Related: Move over, Stegosaurus, there’s a new armored dino in town.]

The reasons for the long neck—and exact mechanics of how it worked—are still a mystery, but some paleontologists believe they could have evolved so the giant creatures could sit still in one spot and still have access to lots of leafy trees to eat. They could have also allowed the sauropod to shed extra heat by increasing their surface area. 

“It could have also been to do with sexual display or used for neck-butting contests between males fighting over mates and territory, similar to how giraffes behave today,” Barett said. “But we can’t say for sure. At this point, it’s pure speculation as to why they evolved necks of this length.”

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The waters of the 360-million-year-old subcontinent Gondwana were a dangerous place for a swim. A killer, bony fish the length of an adult California sea lion stalked freshwater rivers as a top predator. It was massive—as a new discovery reveals, this was the largest prehistoric bony fish ever discovered in southern Africa. 

Its ferocity is reflected in its name, Hyneria udlezinye (H. udlezinye), which means the “one who consumes others,” in IsiXhosa, an Indigenous language spoken widely in southeastern South Africa where its bones were found.

[Related: One wormy Triassic fossil could fill a hole in the evolutionary story of amphibians.]

“Picture a fish looking a bit like a gigantic alligator. About 8 feet long, but with a more rounded head like the front end of a torpedo,” Per Ahlberg, a paleontologist and zoologist at Uppsala University in Sweden, tells PopSci. Ahlberg is the co-author of a study published February 22 in the journal PLOS One describing the carnivore. “The small eyes are located near the front of the head. In the mouth there were rows of small pointed teeth together with pairs of large fangs, up to a couple of inches tall.”

The specimen was found on the edge of Makhanda, South Africa, at the Waterloo Farm lagerstatte, a fossil site rich in specimens from the Late Devonian world, about 419.2 million and 358.9 million years ago. Co-author Rob Gess, a paleontologist from the Albany Museum and Rhodes University, South Africa has been collecting specimens from the site since 1985, where he has uncovered bones, teeth, and small invertebrates, as well as weeds and plants. 

“This fossil site is globally significant for understanding biogeography of the Late Devonian world as it provides us with the only known window into a polar ecosystem during this pivotal time interval,” Gess tells PopSci.

But the remains of bigger things lurk there, too. H. udlezinye belongs to an extinct group of lobe-finned fish called the Tristichopterids. Late in the Devonian period, one branch of the Tristichopterid family developed into a cluster of giants. These huge Tristichopterids possibly arose in Gondwana, the ancient supercontinent, before migrating to Euramerica. The study authors determined that H. udlezinye is closely related to its North American cousins by comparing it with specimens of Hyneria lindae found in Pennsylvania’s Catskill Formation. The authors say that this supports the idea that all of these giants originated in Gondwana and adds a piece to their evolutionary puzzle.

[Related: Tiktaalik’s ancient cousin decided life was better in the water.]

All other fish in the Tristichopterid group were largely believed to live in the more tropical, or central, regions of the subcontinent, but these specimens were found south of where the paleoantarctic circle (our southern polar circle) was at this time. This suggests a more global distribution of the fish, from the equator down closer to the poles. 

H. udlezinye was a ferocious predator that would have eaten most of the larger kinds of fish—including the relatives of modern coelacanths—and four-legged animals found near the site. Their body shape also suggests that they were likely “lie-in-wait predators,” who quietly hid and then quickly lunged to grab passing prey with fanged jaws. 

As fearsome as it must have been, this apex predator was not completely invulnerable. The Tristichopterids, along with many other species of lobe-finned and armor-plated fish, “went extinct in the End Devonian Mass Extinction event 358.9 million years ago—the second of the big five global extinction events that radically altered the make-up of life on Earth,” explains Gess.

Learning more about the Denovian world can help scientists better understand not only the flora and fauna that went extinct during this mass extinction event, but also more about evolution and even ourselves as humans.

“This was a particularly interesting time in the history of the planet, when life had recently become established on land and was diversifying rapidly,” Ahlberg says. “Our own distant ancestors”—the earliest animals with four limbs, or tetrapods—“emerged out of the water during the Devonian.” 

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Roughly 125 million years ago, when the world was warmer, more humid, with higher sea levels, Spinosaurs were a genus of theropod (or “beast-footed”) dinosaurs. These unusual 13 to 22 ton dinos were known for their long, crocodile-like jaws and cone shaped teeth. They stalked riverbanks preying on large fish and lived a different lifestyle than more familiar theropods, such as Allosaurus and Tyrannosaurus. Some spinosaur species include Spinosaurus aegyptiacus and Spinosaurus marocannus and many specimens have been found in northern Africa.

But, paleontologists still don’t know quite as much about these “enormous river monsters.”

An international team of scientists has reconstructed the brains and inner ears of two spinosaur specimens found in England.  Not only does reconstructing a dino brain sound awesome, it’s also a step in understanding how these theropod dinosaurs interacted with their environment. The study was published February 13 in the Journal of Anatomy.

[Related: Cushy feet supported sauropods’ gigantic bodies.]

In order to get a better understanding of how their brains and senses evolved, the team scanned fossils of two different theropod species—Baryonyx found in Surrey, in southern England and Ceratosuchops, which was found on the Isle of Wight. Baryonyx was about 32 feet long and bore the same crocodile-like mouth. Ceratosuchops has been nicknamed the “hell heron,” and was about 27 feet long.

These specimens are special because they are two of the oldest spinosaur fossils that contain the dinosaur’s braincase material. The team was able to digitally reconstruct the internal soft brain tissues that rotted away over time.

They found that the olfactory bulbs—responsible for processing smells—weren’t particularly developed. However, their ears were likely attuned to picking up low frequency sounds. They also found that the parts of the brain that keep the head stable and eyes fixed on prey were possibly less developed than they were in more specialized spinosaurs that evolved later on.

“Despite their unusual ecology, it seems the brains and senses of these early spinosaurs retained many aspects in common with other large-bodied theropods – there is no evidence that their semi-aquatic lifestyles are reflected in the way their brains are organized,” said Chris Barker, a PhD student at the University of Southampton and co-author, in a statement.

One of the team’s interpretations of this evidence is that the ancestors of spinosaurs already had sensory adaptations and brains that were suited to catching fish. To become more adept at living in a specialized semi-aquatic lifestyle, they needed to evolve an unusual snout and teeth.  

[Related: Spinosaurus bones hint that the spiny dinosaurs enjoyed water sports.]

“Because the skulls of all spinosaurs are so specialized for fish-catching, it’s surprising to see such ‘non-specialised’ brains,” said University of Southampton paleontologist and co-author Darren Naish, in a statement. “But the results are still significant. It’s exciting to get so much information on sensory abilities – on hearing, sense of smell, balance and so on – from British dinosaurs. Using cutting-edge technology, we basically obtained all the brain-related information we possibly could from these fossils.”

One of the most powerful CT scanners in Great Britain scanned the braincase of the Cretaceous era-Ceratosuchops, and a model of its brain will be on display alongside of its bones at Dinosaur Isle Museum on the Isle of Wight.

“This new research is just the latest in what amounts to a revolution in paleontology due to advances in CT-based imaging of fossils,” said co-author Lawrence M. Witmer, professor of anatomy at the Ohio University Heritage College of Osteopathic Medicine, in a statement. “We’re now in a position to be able to assess the cognitive and sensory capabilities of extinct animals and explore how the brain evolved in behaviorally extreme dinosaurs like spinosaurs.”

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Dinosaur Mysteries digs into the secretive side of the “terrible lizards” and all the questions that keep paleontologists up at night.

“AND THAT’S HOW YOU MAKE a baby dino-sawr.” I wish it were as easy as Mr. DNA made it sound in the first Jurassic Park movie. Paleontologists have learned an astonishing amount about the “terrible lizards” in the past 200 years, from the colors of their feathers to the illnesses that left them with dino-sores, but there is one area of their lives that we know shockingly little about. We can be sure dinosaurs had sex to make generation after generation of reptiles, but thanks to the rarity of soft tissues in the fossil record, we are still left stumped by how they did it exactly. 

Peeking into the science of prehistoric proliferation isn’t voyeuristic. Sex is something life on Earth does with creativity and gusto. It’s the way that many organisms combine their individual genes and inevitably create new variations. These new traits—a different shade of scale, longer wing feathers, better resistance to infection—make a difference in survival and who mates with whom to pass on some of those traits. When we’re talking about evolution, we’re often just breaking down sex and its consequences. So as far as non-avian dinosaurs are concerned, we’re only just beginning to dig in.

A single fossil discovery could almost solve the problem in an instant. Paleontologists have found other prehistoric creatures whose quest for the “little death” became a more permanent one. In 2012 they reported on fossil turtles preserved in the middle of mating. The next year, a different research team reported on insects called froghoppers smooshed in the throes of arthropod passion 165 million years ago. In 2015, experts announced that 385-million-year-old armored fish had complementary fin modifications for mating, making them among the earliest known vertebrates to have penetrative sex. Which means it’s not impossible that a pair of Velociraptor or other dinosaur was preserved in flagrante in strata, maybe even with some of those mysterious soft parts.

But experts have yet to get lucky. The fossil record is incomplete and unevenly preserved, and it’s doubtful that universities or government funding agencies are going to start signing checks to search for how dinosaurs made the bed rock. Paleontologists have to work with the information they have without making museum security guards wonder why they’re taking such an interest in the back half of that Apatosaurus skeleton.

The nature of dinosaur reproductive organs is as good a place to start as any. Just last year, scientists announced that they had finally delineated the anatomy of a dinosaur’s butthole. A specimen of the horned Psittacosaurus found in Mongolian rocks from more than 100 million years ago came intact with the skin and some internal details for the area just under the tail. The parrot-beaked reptile had a cloaca—a single-use external opening at the end of the urinary, excretory, and reproductive tracts. (No wonder the term means “sewer” in Latin.) But the find confirms what paleontologists already expected based on the fact that both birds—which are living dinosaurs—and crocodiles have cloacae. And that might tell us something about what that vent held.

Dinosaur genitals certainly were not one-size-fits-all. During the Triassic, Jurassic, and Cretaceous periods, wildlife thrived in all sorts of shapes and sizes, which probably means dinosaur sex organs varied too. What was true for Psittacosaurus may not have held for Tyrannosaurus, Stegosaurus, or any other species. (In fact, famous as T. rex is, we don’t have any direct evidence of how they courted, mated, laid eggs, or nested, leaving us to hypothesize details from various relatives.) But we can be reasonably confident that non-bird dinosaurs had clitorises and phalluses, which is also a great statement to drop into the middle of cocktail party chatter.

With the exception of intersex reptiles, female alligators and crocodiles have a clitoris behind their vent, while males have a phallus. Many species of modern birds, too, have similar structures. Emus, ducks, and others have phalluses, and females of some avian species have clitorises—although the sexism prevalent in biology has kept us from drawing a full account. But the fact that the closest living relatives of Brachiosaurus and family had clitorises and phalluses hints that many prehistoric dinosaurs did too. In fact, sometimes it’s difficult to imagine how these beasts could have mated without organs to bridge the distance. While some songbirds bring their gametes into contact through a short “cloacal kiss,” it’s unlikely that amorous Ceratosaurus did the same with their huge bodies and lengthy tails.

But there’s more to sex than mechanics, of course. While we wait for a juicy fossil discovery, we can say a little bit about the moments leading up to mating in the Mesozoic. In recent years paleontologists have begun to reassess the horns, spikes, plates, and other “bizarre” structures that make long-dead reptiles endlessly fascinating. Most of these structures were once seen as weapons for attack and defense. Now, many of them seem to be biological signposts that only developed as the animals matured—sexual selection signals that were meant to be read by potential mates and rivals. So, an Ankylosaurus dotted with bony armor from its eyelids to its tail club didn’t evolve that look to only defend against tyrannosaur teeth: that was Late Cretaceous fashion brought about by season after season of dinosaur-mating choices.

Researchers have even found some of the places where singles flaunted their assets. They’ve used several fossil sites in Colorado to document where Allosaurus-like dinosaurs scraped at the ground with their taloned hind feet, scratching and kicking to impress other members of their kind just as puffins and other birds do today. Dinosaur displays were probably as unique and varied as their species were, but these tracks indicate that some big carnivores preferred a soil-spattered shuffle to start the romance. Perhaps, as fossil track expert Anthony Martin mused in his book Dinosaurs Without Bones, one day an expert or amateur will find tracks of a mating pair that will help us break down the dance steps like an archaic TikTok video.

As long as we have to rely on rare clues from a fragmentary record, the sex lives of dinosaurs will always be incomplete. Whatever we might still learn is held close by the rock. Rather than being a silly aside, however, the question of how dinosaurs reproduced is part of their enduring success story, a truly vital part of ancient lives that we can just barely touch through tooth and bone. They didn’t make it for more than 200 million years without doing something right. 

We hope you enjoyed Riley Black’s column, Dinosaur Mysteries. Check back on PopSci+ in March for the next article.

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With some species clocking in the same size as present day whales, titanosaurs were some of the largest dinosaurs to ever walk the Earth. Living from the Late Jurassic Epoch (about 163.5 million to 145 million years ago) up until the end of the Cretaceous Period (roughly 145 million to 66 million years ago), these herbivorous sauropod dinosaurs ranged from 23 to 85 feet long, depending on the species.

Now, a discovery of these dinosaurs in one of their smallest forms is revealing intimate details about the lives of these gentle giants. In excavations between 2017 and 2020, a team of researchers discovered more then 250 fossilized eggs in 92 nesting sites in central India’s Lameta Formation The findings are detailed in a study published January 18 in the open-access journal PLOS ONE.

[Related: A fossilized egg laid by an extinct, human-sized turtle holds a rare jackpot.]

The Lameta Formation in the Narmada Valley is well known for fossils of dinosaur eggs and skeletons from the Late Cretaceous Period. Scientists first found dinosaur eggs in the region in the 1990s, and this study focuses on on a nesting site in the Dhar district.

“Together with dinosaur nests from Jabalpur in the upper Narmada valley in the east and those from Balasinor in the west, the new nesting sites from Dhar District in Madhya Pradesh (Central India), covering an east-west stretch of about 1000 km [621 miles], constitute one of the largest dinosaur hatcheries in the world,” said Guntupalli V.R. Prasad, a study co-author also from the University of Delhi, in a statement.

The team closely examined the eggs, which clocked in at roughly six inches in diameter, and identified six different egg-species, called oospecies. The variation suggests that there was a higher diversity of titanosaur species than is currently represented by the fossilized skeletal remains found in this region.

“Our research has revealed the presence of an extensive hatchery of titanosaur sauropod dinosaurs in the study area and offers new insights into the conditions of nest preservation and reproductive strategies of titanosaur sauropod dinosaurs just before they went extinct,” said Harsha Dhiman from the University of Delhi, the lead author of the study, in a statement.

The team also believes that titanosaurs buried their eggs in shallow pits similar to present-day crocodiles based on the layout of the nests. They even found a rare case of an ovum-in-ovo (or egg-in-egg), which indicates that titanosaur sauropods had reproductive physiology that is similar in modern birds and crocodiles and possibly laid their eggs sequentially.

Since many nests were found in the same area, the dinosaurs may have exhibited the colonial nesting behavior seen in present day birds like great egrets, brown pelicans, and cormorants. However, the close spacing of the nests didn’t leave a lot of room for adult dinosaurs, which supports the idea that adult titanosaurs left their newborns to fend for themselves, unlike modern birds who sit on their eggs to incubate them.

[Related: This newly discovered titanosaur had heart-shaped tail bones.]

Historically, the details of dinosaur reproductive habits have been a bit difficult to determine. Fossil nests can help and the ones from this study offer insight into how some of the largest dinosaurs in history reproduced, evolved, and lived just before going extinct.

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Deep in the stone at the Berlin-Ichthyosaur State Park (BISP) in Nevada’s Humboldt-Toiyabe National Forest, many 50-foot-long ichthyosaur (Shonisaurus popularis) specimens lay petrified and frozen in time. This order of extinct marine reptiles (and Nevada’s state fossil) looked like a chunky dolphin and lived during the late Triassic age, roughly 237-227 million years ago.

New research also suggests that the predator may have performed similar migrations to modern whales. Today’s blue and humpback whales make annual migrations thousands of miles across oceans to breed and give birth in regions where predators are scarce. Many of these whales gather together year after year along the same stretches of coastline.

[Related: These ancient, swimming reptiles may have been the biggest animals of all time.]

Shonisaurus may have done something very similar. An international team of researchers published their findings Monday in the journal Current Biology, explaining how at least 37 of these marine reptiles died in the same location—a question that has stumped paleontologists for more than 50 years.

“We present evidence that these ichthyosaurs died here in large numbers because they were migrating to this area to give birth for many generations across hundreds of thousands of years,” said co-author and Smithsonian National Museum of Natural History curator Nicholas Pyenson, in a statement. “That means this type of behavior we observe today in whales has been around for more than 200 million years.”

Some paleontologists have proposed that BISP’s ichthyosaurs died in a mass stranding event similar to the ones seen in whales today, or that a harmful algal bloom may have poisoned the animals. But these hypotheses do not have strong scientific evidence supporting them.

To try to solve this prehistoric puzzle, the team combined 3D scanning and geochemistry and combed through archival materials, photographs, maps, and field notes, for shreds of evidence.

Within BISP is a barn-like building that researchers call Quarry 2, which houses partial skeletons from an estimated seven individual ichthyosaurs that all appear to have died around the same time. 

“When I first visited the site in 2014, my first thought was that the best way to study it would be to create a full-color, high-resolution 3D model,” lead author Neil Kelley, an assistant professor of geology at Vanderbilt University, said in a statement. “A 3D model would allow us to study the way these large fossils were arranged in relation to one another without losing the ability to go bone by bone.”

The team then collaborated with Jon Blundell, a Smithsonian Digitization Program Office’s 3D Program team member, and Holly Little, informatics manager in the museum’s Department of Paleobiology. Little and Blundell used digital cameras and a spherical laser scanner to take hundreds of photographs and millions of point measurements. These were then stitched together using specialized software to create a 3D model of the fossil bed while the paleontologists on the team physically measured the bones.

“Our study combines both the geological and biological facets of paleontology to solve this mystery,” co-author Randall Irmis, a paleontology professor at the University of Utah and the chief curator of the Natural History Museum of Utah’s Department of Geology & Geophysics, said in a statement. “For example, we examined the chemical make-up of the rocks surrounding the fossils to determine whether environmental conditions resulted in so many Shonisaurus in one setting. Once we determined it did not, we were able to focus on the possible biological reasons.”

Geochemical tests in the rock didn’t reveal any signs that these ichthyosaurs died due to a major environmental event like a harmful algal bloom that would have also disturbed the ecosystem. They expanded their search beyond Quarry 2 to the surrounding geology and fossils that scientists had previously excavated from the area. 

[Related: This whale fossil could reveal evidence of a 15-million-year-old megalodon attack.]

The geologic evidence showed that when the ichthyosaurs died, their bones sank to the bottom of the sea over time instead of collecting along the shoreline, which would have suggested stranding. The area’s mudstone and limestone were also full of large adult Shonisaurus specimens but not as many specimens of other marine vertebrates.

“There are so many large, adult skeletons from this one species at this site and almost nothing else,” said Pyenson. “There are virtually no remains of things like fish or other marine reptiles for these ichthyosaurs to feed on, and there are also no juvenile Shonisaurus skeletons.”

After ruling out the algae and stranding hypotheses, the team found a key clue in tiny ichthyosaur remains among some of the new fossils collected at the park and hiding within older museum collections. Micro-CT x-ray scans and a comparison of the bones and teeth showed that the small bones were embryonic and newborn Shonisaurus.

“Once it became clear that there was nothing for them to eat here, and there were large adult Shonisaurus along with embryos and newborns but no juveniles, we started to seriously consider whether this might have been a birthing ground,” said Kelley.

Additional analysis revealed that the ages of the many fossil beds of BISP were actually separated by at least hundreds of thousands of years, if not millions of years.

“Finding these different spots with the same species spread across geologic time with the same demographic pattern tells us that this was a preferred habitat that these large oceangoing predators returned to for generations,” said Pyenson. “This is a clear ecological signal, we argue, that this was a place that Shonisaurus used to give birth, very similar to today’s whales. Now we have evidence that this sort of behavior is 230 million years old.”

The next step for this research is to look into other ichthyosaur and Shonisaurus sites in North America with these new findings in mind. It will help scientists recreate this ancient world by looking for other breeding sites or places with greater diversity of other species that could have provided rich feeding grounds for this extinct apex predator. 

“One of the exciting things about this new work is that we discovered new specimens of Shonisaurus popularis that have really well-preserved skull material,” Irmis said. “Combined with some of the skeletons that were collected back in the 1950s and 1960s that are at the Nevada State Museum in Las Vegas, it’s likely we’ll eventually have enough fossil material to finally accurately reconstruct what a Shonisaurus skeleton looked like.”

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About 252 to 201 million years ago, roughly 76 percent of all marine and land-based species were wiped off the face of the Earth. The Triassic-Jurassic mass extinction is largely believed to be what helped dinosaurs eventually dominate the landscape, but scientists are still understanding how and why. A new study published Friday in the journal Current Biology, suggests that it was climate change and not competition between species that helped them ascend to the top of the food chain.

[Related: After the dinosaurs, Earth became an all-you-can-eat buffet for snakes.]

The sauropod-like dinosaurs that would become the giant herbivore species seen during the Jurassic (such as Diplodocus and Brachiosaurus) thrived and expanded to new territories as the Earth warmed. These dinosaurs are known for their massive bodies with long tails and giraffe-like necks paired with and a small head.

An team of paleontologists from the United Kingdom, Germany, and Brazil compared computer models of global climate conditions, such as rainfall and temperature, with data on the different locations of dinosaurs during this time period. Their work showed how both sauropods and sauropod-like animals were a winner during this turbulent period on Earth.

“What we see in the data suggests that instead of dinosaurs being outcompeted by other large vertebrates, it was variations in climate conditions that were restricting their diversity,” Emma Dunne, study co-author and paleontologist at Friedrich-Alexander University Erlangen-Nürnberg, said in a statement. “But once these conditions changed across the Triassic-Jurassic boundary, they were able to flourish. The results were somewhat surprising, because it turns out that sauropods were really fussy from the get-go: later in their evolution they continue to stay in warmer areas and avoid polar regions.”

[Related: Cushy feet supported sauropods’ gigantic bodies.]

There is still debate among scientists about the direct cause of this extinction event. Some scientists believe that the climate change and sea level rise resulted from a sudden large release of carbon dioxide that occurred when the supercontinent Pangea began to rift, leading to devastating volcanic eruptions. As the land masses that are now now eastern North America and northwestern Africa began to split apart, up to 100,000 gigatons of carbon dioxide may have been released into the atmosphere. This extra carbon dioxide likely strengthened the greenhouse effect around the world, increasing air temperatures by as much as 18-27 °F.

Further research will go into better understanding the effect of climate change after the dinosaurs took over.

“What we want to do next is use the same techniques to understand the role of climate in the next 120 million years of the dinosaur story,” said Richard Butler, a paleontologist at the University of Birmingham, in a statement.

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When the discovery of a new species of ankylosaur (Zuul crurivastator) was announced, it delighted 80s movie fans the world over due to its resemblance to the monster Zuul from the 1984 classic Ghostbusters. The dinosaur’s name means, “Zuul, the destroyer of shins,” in reference to its 10 foot long tail that was likely used to smash the legs of two legged tyrannosaurs like the Tyrannosaurus rex.

Now, scientists from the the Royal Ontario Museum (ROM), Royal BC Museum, and North Carolina Museum of Natural Sciences have found new evidence for how these tank-like armored dinosaurs used these signature tail clubs. Their study was published today in the journal Biology Letters.

[Related: This new species of dinosaur looks like Zuul from Ghostbusters.]

A very complete and well-preserved fossil of Zuul crurivastator housed at the Royal Ontario Museum has spikes along its flanks that were broken and actually re-healed while the dinosaur was still living. Scientists believed that these injuries were caused from a strike by another ankylosaur’s massive tail club.

The team suggests that ankylosaurs had complex social behavior, potentially battling one another for territorial and social dominance or even engaging in a rutting season for mates the way many animals like deer and elk do. In animals alive today, specialized weapons like the antlers of deer or the horns of antelopes evolved to be used mostly for fighting off members of the same species during battles for territory or mates.

The plant-eating dinosaur lived throughout the United States and Canada during the late Cretaceous Period, about 74-67 million years ago. The Zuul skeleton used in this study was found in the famed fossil-rich Judith River Formation of northern Montana.

Initially, Zuul’s skull and tail had been freed from the surrounding rock, while its body was still enclosed in 35,000 pounds of sandstone. The body was exhumed after years of work, and had most of the skin and bony armor across the entire back and flanks in tact. This gave scientists a remarkable view of what the dinosaur actually looked like when it roamed the Earth.

Zuul’s body was covered in bony plates of different shapes and sizes and the ones along its sides were particularly large and spiky. Some of the spikes near the dinosaurs hips are missing their tips and the bone and horny sheath appears to have healed into a more blunt shape. The team believes that the pattern of these injuries possibly comes from some form of ritualized ankylosaur combat, or jousting with their tail clubs. They also weren’t likely caused by an attacking predator like a T-rex due to the locations of the injuries on the skeleton.

“I’ve been interested in how ankylosaurs used their tail clubs for years and this is a really exciting new piece of the puzzle,” said study co-author Victoria Arbour, Curator of Palaeontology at the Royal BC Museum, in a statement. “We know that ankylosaurs could use their tail clubs to deliver very strong blows to an opponent, but most people thought they were using their tail clubs to fight predators. Instead, ankylosaurs like Zuul may have been fighting each other.”

[Related: Move over, Stegosaurus, there’s a new armored dino in town.]

The back half of the ankylosaur’s tail was stiff and the tip was covered in huge bony blobs, making the tail a pretty fierce sledgehammer-like weapon. The new research shows that the tail clubs could have been used for inter-species combat as well as a defense against bigger predators and that this conflict within the species likely drove their evolution.

“The fact that the skin and armour are preserved in place is like a snapshot of how Zuul looked when it was alive. And the injuries Zuul sustained during its lifetime tell us about how it may have behaved and interacted with other animals in its ancient environment,” said David Evans, Temerty Chair and Curator of Vertebrate Palaeontology at the Royal Ontario Museum, in a statement.

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It might be time for the megalodon to move over and make room for a new ancient aquatic animal. There’s a newly discovered dinosaur species that may also be pretty good swimmer with duck-like diving abilities.

Natovenator polydontus was a theropod (a hollow-bodied dinosaur) that had three toes and claws on each limb. It lived about 145 to 66 million years ago in Mongolia, during the Upper Cretaceous period. Its recent discovery was outlined in a study published last week in the journal Communications Biology. The name Natovenator polydontus means “many-toothed swimming hunter.”

[Related: Were dinosaurs warm-blooded or cold-blooded? Maybe both.]

One of the similarities that Natovenator has with modern, diving birds is it’s streamlined ribs.

“Whereas diving birds are well known to have streamlined bodies, such body shapes have not been documented in non-avian dinosaurs,” wrote the authors in the study. “Its body shape suggests that Natovenator was a potentially capable swimming predator, and the streamlined body evolved independently in separate lineages of theropod dinosaurs.”

The specimen that the team from Seoul National University, the University of Alberta, and the Mongolian Academy of Sciences examined in this study is similar to Halszkaraptor, another dinosaur that was discovered in Mongolia. Scientists believe Halszkaraptor was likely semiaquatic, but the Natovenator specimen in the study is more complete than one of the Halszkaraptor. This makes it easier for scientists to see Natovenator’s streamlined body shape.

Natovenator is a cousin of the famous Velociraptor, but has a much more streamlined look, with its long jaws and tiny teeth. The specimen was discovered at a spot in the Gobi Desert called Hermiin Tsav or (Khermen Tsav), which is a hot spot for preserving multiple dinosaur species.

David Hone, a paleontologist and professor at Queen Mary University of London, told CNN that it is difficult to say exactly where the new species falls on the spectrum of totally land-dwelling animals to totally aquatic animals. However, the specimen’s arms, “look like they’d be quite good for moving water,” he said. Hone participated in the peer review for this study.

[Related: Spinosaurus bones hint that the spiny dinosaurs enjoyed water sports.]

According to Hone, the next steps to understand Natovenator’s motion should be modeling of the dinosaur’s body shape to help scientists understand exactly how it might have moved. “Is it paddling with its feet, a bit of a doggy-paddle? How fast could it go?”

Additional research should also look back at the environment in which Natovenator lived. “There is a real question of, OK, you’ve got a swimming dinosaur in the desert, what’s it swimming in?” Hone said. “Finding the fossil record of those lakes is gonna be tough, but sooner or later, we might well find one. And when we do, we might well find a lot more of these things.”

In addition to biomechanical studies that will test how Natovenator and related water-dwelling species moved around, studies of geochemical clues in the dinosaur’s teeth and bones, will either confirm or challenge the idea that Natovenator was as strong a swimmer as the study suggests.

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A new fossil find in the United Kingdom is a victory for de-cluttering and organization enthusiasts everywhere.

The fossil specimen of an ancestor of present day lizards first unearthed in the 1950s was recently found stored in a cupboard at the Natural History Museum in London. The discovery potentially shows that today’s lizards likely originated in the Late Triassic period (about 200 million years ago) and not during the Middle Jurassic as previously believed.

[Related: A Scottish fossil is helping scientists fill the gaps in the lizard family tree.]

The findings are described in a paper published today in the journal Science Advances. The team named their discovery Cryptovaranoides microlanius, which means meaning “small butcher,” as a tribute to the animal’s jaws filled with sharp-edged slicing teeth.

“I first spotted the specimen in a cupboard full of Clevosaurus fossils in the storerooms of the Natural History Museum in London where I am a Scientific Associate,” said David Whiteside, from the University of Bristol’s School of Earth Sciences and a co-author of the paper, in a statement. “This was a common enough fossil reptile, a close relative of the New Zealand Tuatara that is the only survivor of the group, the Rhynchocephalia, that split from the squamates over 240 million years ago.

The specimens were originally unearthed from a quarry in southwest England.

“Our specimen was simply labelled ‘Clevosaurus and one other reptile.’ As we continued to investigate the specimen, we became more and more convinced that it was actually more closely related to modern day lizards than the Tuatara group,” Whiteside added. “We made X-ray scans of the fossils at the University, and this enabled us to reconstruct the fossil in three dimensions, and to see all the tiny bones that were hidden inside the rock.”

The age of the new fossil impacts the general estimates of when Squamata, the order of reptiles that includes lizards and snakes, evolved, how quickly they evolved, and even what triggered the general origin of the order.

The study shows that Cryptovaranoides is clearly a squamate due to multiple features including its braincase (which encloses the brain), neck vertebrate, upper median tooth in front of the mouth, and the way that the teeth are set on a shelf in the jaws. It also has features seen in more primitive squamates, including an opening on one side of the end of the upper arm bone (the humerus) where a nerve and an artery pass through and few rows of teeth on the bones making up the roof of the lizard’s mouth.

[Related: These tiny ‘dragons’ flew through the trees of Madagascar 200 million years ago.]

“In terms of significance, our fossil shifts the origin and diversification of squamates back from the Middle Jurassic to the Late Triassic,” says co-author Mike Benton a palentologist also from the University of Bristol, in a statement. “This was a time of major restructuring of ecosystems on land, with origins of new plant groups, especially modern-type conifers, as well as new kinds of insects, and some of the first of modern groups such as turtles, crocodilians, dinosaurs, and mammals.

Adding in older modern squamates help complete this evolutionary picture as the Earth rebuilt after the end-Permian mass extinction, which killed about 95 percent of the Earth’s marine species and 70 percent of land species about 252 million years ago.

“The name of the new animal, Cryptovaranoides microlanius, reflects the hidden nature of the beast in a drawer but also in its likely lifestyle, living in cracks in the limestone on small islands that existed around Bristol at the time,” Sofia Chambi-Trowell, co-author and PhD research student at the University of Bristol said in a statement.

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It looks like Tyrannosaurus rex has another relative to add to its ever-growing family tree. In 2017, Badlands Dinosaur Museum crew member Jack Wilson spotted the remains of what turned out to be a new species of tyrannosaur, named Daspletosaurus wilsoni, or D. wilsoni. Wilson first saw a small, flat piece of bone projecting out of the bottom of a cliff at the Judith River Formation in northeastern Montana. The fossil Wilson spotted turned out to be part of the dinosaur’s nostril.

Additional fossils were uncovered between 2017 and 2021, including skeletal fragments of a rib and toe bone and parts of a fossilized skull. Those bits were enough to determine this was a new species, as detailed in a paper published on November 25 in the journal Paleontology and Evolutionary Science. The remains date back to 76.5 million years ago, during the Cretaceous period, millions of years before T. rex stomped through the Late Cretaceous.

[Related: Is T. rex really three royal species? Paleontologists cast doubt over new claims.]

One of D. wilsoni‘s unique features is an arrangement of spiked hornlets around its eyes. It also has a mix of attributes that were found in more primitive types of tyrannosaurs, such as prominent set of horns around the eye. It also boasts physical features more common in later members of this group, including the famed T. rex. One of these more advanced tyrannosaur features is a tall eye socket and expanded air-pockets inside of the skull.

“In this way, D. wilsoni is a ‘halfway point’ or  ‘missing link’ between older and younger tyrannosaur species,” wrote study authors Elías Warshaw, a paleontology student at Montana State University and Denver Fowler, a paleontologist and curator of Badlands Dinosaur Museum, in a statement.

The Tyrannosaur family is large: It has nine genera, which falls above species and below family in the system that classifies animal and plants. The family includes a genus of predators called daspletosaurs, which lived about 79.5 million and 74 million years ago, during the Late Cretaceous Period. The team believes that D. wilsoni is an intermediate daspletosaur, the descendant of Daspletosaurus torosus, and the predecessor of Daspletosaurus horneri. Daspletosaurus is Greek for “frightful lizard,” and the specimen was nicknamed Sisyphus, in reference to the myth of the man cursed to push a boulder up a hill for eternity. It took an enormous amount of effort to extract the bones from the surrounding rock, including removing about 25 feet of stone from the top of the skeleton.

In North America during the Late Cretaceous, multiple closely related species made up the evolutionary families of dinosaurs. It was previously thought that these species lived at the same time, which would be evidence of what biologists call branching evolution.  However, newly discovered specimens such as this one and a better understanding of when the animals lived has changed how paleontologists understand dinosaur evolution.

[Related: The T. rex ‘dynasty’ reigned for more than 125,000 generations.]

“We can now see that many of these species are actually very finely separated in time from each other, forming consecutive ladder-like steps in a single evolutionary lineage where one ancestral species evolves directly into a descendant species,” wrote Warshaw and Fowler.

This process is called anagenesis, or linear evolution. It is different from cladogenesis evolution, where successive branching events create many closely related species that that look similar but are evolutionary “cousins,” not descendants and ancestors.

“The new study supports the addition of tyrannosaurs to a growing list of dinosaurs (including horned and duckbilled dinosaurs) for which anagenesis (linear evolution) has been proposed,” said Warshaw and Fowler. This suggests that linear evolution may be more widespread in dinosaurs and that branching evolution occurs less frequently than previously thought.

Warshaw is currently conducting more detailed research into the link between T. rex and Daspletosaurus.

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While lizards and dinosaurs trotted the Earth together, lizards were the one of the newer animals on the block during the Middle Jurassic period. Scientists are still unraveling their unique history. Now, roughly 166 million years later, a nearly-complete fossil of a lizard skeleton is helping scientists fill in some of those evolutionary gaps.

The specimen was discovered on Scotland’s Isle of Skye and is called Bellairsia gracilis. Bellairsia was a tiny lizard ancestor and was only about two inches long. The “exceptional” new fossil is described in a study published this week in Nature. The fossil is only missing its snout and tail and is likely the most complete fossil lizard of this age anywhere in the world.

[Related: This 6-inch-long Jurassic creature does a great lizard impersonation.]

Within Bellairsia‘s skeleton are a mixture of older ancestral features and modern features, which provides evidence of what the ancient ancestor of present-day lizards might have looked like. “This little fossil lets us see evolution in action,” said first author Mateusz Tałanda from the University of Warsaw and University College London, in a statement. “In paleontology you rarely have the opportunity to work with such complete, well-preserved fossils coming from a time about which we know so little.”

A team led by Oxford University and the National Museums Scotland first found the fossil in 2016. In addition to its beautiful scenery, the Isle of Skye is a hot spot for fossils (including ones from extinct amphibians and mammals) that is giving scientists a window into how present-day animal groups evolved through time.

“Bellairsia has some modern lizard features, like traits related to cranial kinesis–that’s the movement of the skull bones in relation to one another. This is an important functional feature of many living squamates,” Tałanda said.

Squamates are a huge present-day animal group that includes lizards, snakes, chameleons, and geckos. With more than 10,000 species of squamates living today, they are one of the most species-rich living vertebrate animal groups. The smallest living squamate is the Virgin Islands Dwarf Sphaerodactylus, coming in at only about an inch long and less than one-tenth of an ounce. The Komodo Dragon is the largest living squamate, which has been known to reach about 10 feet long and weigh over 350 pounds.

[Related: This pterosaur ancestor was a tiny, flightless dog-like dinosaur.]

Elsa Panciroli from the Oxford University Museum of Natural History and National Museums Scotland is one of the study’s co-authors and also was the lucky scientist to first discover the fossil. “It was one of the first fossils I found when I began working on Skye,” Panciroli said in a statement. “The little black skull was poking out from the pale limestone, but it was so small I was lucky to spot it. Looking closer I saw the tiny teeth, and realized I’d found something important, but we had no idea until later that almost the whole skeleton was in there.”

While scientists know that the earliest origins of squamates lie about 240 million years ago during the Triassic period, a lack of fossils from both the the Triassic and Jurassic period has made their early evolution and anatomy difficult to trace. Analyzing the new fossil alongside some living and extinct squamates shows that Bellairsia belongs to the “stem” of the squamate family tree. It likely split from other lizards just before modern groups of lizards arose. It also supports the idea that geckos branched out early and that Oculudentavis is actually a stem on the squamate family tree and not a dinosaur.

“Fossils like this Bellairsia specimen have huge value in filling gaps in our understanding of evolution and the history of life on Earth,” said co-author Roger Benson from the University of Oxford, in a statement. “It used to be almost impossible to study such tiny fossils like this, but this study shows the power of new techniques including CT scanning to image these non-destructively and in great detail.”

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In case a tarantula nebula and a skeleton galaxy weren’t enough spookiness for one Halloween, scientists are learning more about dinosaur mummies. About 67 million years ago, a duck billed dinosaur called Edmontosaurus was going about its business in what is now North Dakota. The reptile died, but that wasn’t the end of Edmontosaurus’ troubles. A hungry ancient relative of the crocodile snuck in and started to munch on Edmontosaurus’ body, marking up its bones along the way. This hungry croc wasn’t good at destroying the evidence of its lunch, as the fossilized remains of Edmontosaurus’ skin contain well-preserved bite marks.

While this isn’t the fist dinosaur mummy to be discovered, they are a historically rare find. Typically, fossilized skin forms when the carcass of a dinosaur was protected from becoming a predator’s snack due to a quick burial and/or desiccation. Desiccation is when the moisture is sucked out of the skin of a living organism and deflated is when it shrinks down.

Dinosaur “mummies” have well preserved skin like those of this Edmontosaurus, but this specimen was different because of its crocodile wounds. The bite marks left behind from a posthumous but pre-mummy attack can help scientists uncover more about how this skin is so well preserved even after millions of years. In a new study published in the journal PLOS One, researchers looked at both fossil evidence and modern animal carcasses to propose a new explanation for how prehistoric dinosaur mummies might form. Based on this new explanation, the study suggests that there may even be more dino mummies out there just waiting to be found.

[Related: Feast your eyes on exquisite fossils from an ancient rainforest (and more).]

For the study, Stephanie Drumheller, a palentologist from the University of Tennessee, Knoxville, and colleagues looked at the Edmontosaurus fossil, aptly nicknamed “Dakota,” from the North Dakota Heritage Center and State Museum. Dakota was discovered in 1999 and excavated from the famed Hell Creek Formation, a geological formation shaped roughly 145 million to 66 million years ago near the end of the Cretaceous period and the start of the Paleogene period. Dakota had large patches of dry and seemingly deflated skin on its limbs and tail. The unhealed skin damage from its encounter with ancient crocodiles provides evidence that it became a mummy even though it wasn’t protected from scavengers.

Scavengers, like modern-day vultures, typically go after internal tissues and organs, which leaves behind the skin and bones. The bites to remove the organs helps gasses and liquids escape, helping the skin and bones dry out. The authors of study believe that skin damage from an incomplete scavenging would have exposed the dinosaurs insides, drying out the skin as the remains were buried.

[Related: This whale fossil could reveal evidence of a 15-million-year-old megalodon attack.]

“Not only has Dakota taught us that durable soft tissues like skin can be preserved on partially scavenged carcasses, but these soft tissues can also provide a unique source of information about the other animals that interacted with a carcass after death,” Clint Boyd, senior paleontologist at the North Dakota Geological Survey, said in a press release.

Desiccation and deflation is common with present day carcasses and explains how dinosaur mummies might actually be able to form. But just as every living being is a little different, every death is a little different—and the team suggests that there are possibly many ways for a dinosaurs to become a mummy. Understanding how dino mummification works will guide how paleontologists carefully collect and interpret the remains of even more varieties of long-lost creatures.

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Pterosaurs are some of the stars of the latest chapters of Jurassic Park franchise and the cinematic television streaming series Prehistoric Planet. These giant winged dinosaurs scoured the skies from the late Triassic Period all the way up to the demise of the dinosaurs in the late Cretaceous Period, but they weren’t always so large. Some new clues are revealing just how tiny the ancestors of these winged reptiles once were.

In a study out today in the journal Nature, an international group of scientists discuss their new examination of a Triassic-era fossil that was first discovered 100 years ago in Scotland. Computed Tomography (CT scanning) helped create the first accurate and whole skeleton reconstruction of the non-avian Scleromochlus taylori, revealing physical features that show that it’s a close pterosaur relative. The specimen is within a group known as Pterosauromorpha, an extinct group of reptiles called lagerpetids (which means “rabbit-reptiles”) that are grouped together with the pterosaurs.

[Related: The biggest animal ever to fly was a reptile with a giraffe-like neck.]

“Pterosaurs were the first vertebrates to evolve powered flight and for nearly two centuries, we did not know their closest relatives,” Sterling Nesbitt, a paleontologist and professor from Virgina Tech University, said in a press release. “Now we can start filling in their evolutionary history with the discovery of tiny close relatives that enhance our knowledge about how they lived and where they came from.”

Lagerpetids lived about 240 to 210 million years ago and they were relatively small, even by modern mammal standards. They were generally about the size of a cat or small dog. Schleromochlus was even smaller, at under 7 inches (20 centimeters) in length, a little more than half the size of a standard school ruler. The results of this study support the general hypothesis that the first flying reptiles evolved from small, bipedal ancestors like Schleromochlus.

These findings also settle a 100 year-long debate: Scientists have long disagreed as to whether Scleromochlus were an evolutionary step in the direction of pterosaurs, dinosaurs, or else some other reptile entirely.

[Related: Zimbabwe’s newest dinosaur may be Africa’s oldest.]

“It’s exciting to be able to resolve a debate that’s been going on for over a century, but it is far more amazing to be able to see and understand an animal which lived 230 million years ago and its relationship with the first animals ever to have flown,” said Davide Foffa, a research associate at National Museums Scotland, and a research fellow at the University of Birmingham, in a press release. “This is another discovery which highlights Scotland’s important place in the global fossil record, and also the importance of museum collections that preserve such specimens, allowing us to use new techniques and technologies to continue to learn from them long after their discovery.”

The fossil of Scleromochlus has been difficult to study in depth due to its size and because it is poorly preserved in a block of sandstone. The specimen is part of the Elgin reptiles, a group of Triassic and Permian fossils that were found in the Lossiemouth Sandstone Formation near the town of Elgin in the Morayshire region of northeast Scotland.

“The Elgin reptiles aren’t preserved as the pristine, complete skeletons that we often see in museum displays,” said Paul Barrett, a professor and paleobiologist at the Natural History Museum, in a press release. “They’re mainly represented by natural moulds of their bone in sandstone and—until fairly recently—the only way to study them was to use wax or latex to fill these moulds and make casts of the bones that once occupied them. However, the use of CT scanning has revolutionized the study of these difficult specimens and has enabled us to produce far more detailed, accurate and useful reconstructions of these animals from our deep past.”

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Just off of the western coast of Mexico’s Yucatán peninsula lies the 12 mile deep, 6.2 mile wide Chicxulub crater. The 66 million year-old impact crater is the site where a massive asteroid struck the Earth, wiping out the dinosaurs and about three quarters of all life on Earth. But new evidence shows that it was even more destructive than previously realized.

A study published today in the journal AGU Advances shows that the asteroid also triggered a monstrous tsunami with mile-high waves that scoured the ocean floor thousands of miles from the impact site in Mexico. A team of researchers built the a first global simulation of the Chicxulub impact tsunami to be published in a peer-reviewed journal and reviewed the geological record at over 100 sites around the world to determine the tsunami’s path and power.

“This tsunami was strong enough to disturb and erode sediments in ocean basins halfway around the globe, leaving either a gap in the sedimentary records or a jumble of older sediments,” lead author Molly Range, who conducted the modeling study for a master’s thesis at the University of Michigan, said in a press release.

[Related: If that asteroid had been 30 seconds late, dinosaurs might rule the world and humans probably wouldn’t exist.]

The team estimates that the initial energy in the Chicxulub impact tsunami was up to 30,000 times larger than the energy of the 2004 Indian Ocean earthquake tsunami—a devastating disaster killed more than 230,000 people and was one of the largest tsunamis in the modern record.

To determine just how powerful the tsunami was, the team analyzed the published records of 165 marine boundary sections, or marine sediments in the geologic record deposited around the time the asteroid struck the earth, and sediment cores. The cores act as a terrestrial timeline that scientists can use to analyze the layers or rock, sand, and ice to better understand what the Earth was like millions of years ago.

The K–Pg boundary (also called the K-T boundary) marks around the time where the astroid hits—ending the Cretaceous Period. Through the sediment in these boundary sections, they found that the impact tsunami radiated mainly to the east and northeast (into the North Atlantic Ocean), then later to the southwest through the Central American Seaway which used to separate the continents of North America and South America. Lastly, the tsunami diffused into the South Pacific Ocean.

“The distribution of the erosion and hiatuses that we observed in the uppermost Cretaceous marine sediments are consistent with our model results, which gives us more confidence in the model predictions,” said Range.

The authors also used the boundary section sediment to determine the speed of underwater currents in those basins. In some nearby spots, the current was likely 0.4 miles per hour (20 centimeters per second), a velocity that is strong enough to erode fine-grained sediments on the seafloor. By comparison, the South Atlantic, the North Pacific, the Indian Ocean, and the region that is today the Mediterranean appear to have been largely protected from the strongest effects of the tsunami.

Outcrops of the K-Pg boundary were found on the eastern shores of New Zealand’s north and south islands, over 7,500 miles (12,000 km) from the crater impact site. “We feel these deposits are recording the effects of the impact tsunami, and this is perhaps the most telling confirmation of the global significance of this event,” Range said.

[Related: It was probably springtime when an asteroid did the dinosaurs in.]

To create the computer model of the mass extinction event, a large computer program called a hydrocode simulated the chaotic first 10 minutes of the extinction event. The asteroid in the simulation was modeled after previous studies that found the dinosaur-killing space rock to be 8.7 miles in diameter and moving at 27,000 mph After it struck the Earth’s crust under shallow ocean waters, a 62 mile (100 km) wide crater ejected dense clouds of dust and soot into the atmosphere.

According to the simulation, ejected material formed a 2.8 mile (4.5 km) high wave two and a half minutes after impact which then subsided when the material fell back to Earth. Ten minutes after the projectile hit the Yucatan, a 0.93 mile (1.5 km) high tsunami wave began rolling across the ocean in all directions.

This 10-minute simulation was entered into two tsunami-propagation models (called MOM6 and MOST) used by the National Oceanic and Atmospheric Administration (NOAA) to track and understand these enormous waves. “The big result here is that two global models with differing formulations gave almost identical results, and the geologic data on complete and incomplete sections are consistent with those results,” University of Michigan paleoceanographer and study co-author Ted Moore said in a press release. “The models and the verification data match nicely.”

The simulation mirrored geologic findings, showing that about one hour after impact, the wave had spread outside the Gulf of Mexico and into the North Atlantic. Four hours after impact, the tsunami passed through the Central American Seaway and into the Pacific, and by the end of day one, the waves had crossed most of the Pacific Ocean and entered the Indian Ocean from both sides. By 48 hours after impact, significant tsunami waves had reached most of the coastlines on Earth.

“Depending on the geometries of the coast and the advancing waves, most coastal regions would be inundated and eroded to some extent,” the authors said. “Any historically documented tsunamis pale in comparison with such global impact.”

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About 150 million years ago, Opisthiamimus gregori crawled around Jurassic-era North America, searching for food alongside more famous dinosaurs like Stegosaurus and Allosaurus. It munched on insects and small invertebrates, and, at six inches long, was small enough to fit inside the palm of a modern adult’s hand.

This extinct species belongs to the same ancient lineage as the present-day tuatara reptile, according to new findings from Smithsonian National Museum of Natural History, University College in London, and the London Natural History Museum. Their study, published on September 15 the Journal of Systematic Paleontology, helps explain some of the unique differences between this extinct creature in the New Zealand critter.

O. gregori is a rhynchocephalian, a distinct group that diverged from lizards during the Triassic Period. The tuatara (its only living relative) is exclusively found in present-day New Zealand, looks a little bit like a stout iguana, and is a bit of an enigma: It looks like a lizard, but isn’t a lizard. Lizards belong to an order of reptiles called sqamates, which also includes snakes and worms).

[Related: These lizards use built-in ‘scuba gear’ to breathe underwater.]

“What’s important about the tuatara is that it represents this enormous evolutionary story that we are lucky enough to catch in what is likely its closing act,” said Matthew Carrano, the National Museum of Natural History’s curator of Dinosauria, in a press release. “Even though it looks like a relatively simple lizard, it embodies an entire evolutionary epic going back more than 200 million years.”

A complete and well-preserved O. gregori skeleton was found in northern Wyoming’s Morrison Formation, sitting atop was what once an Allosaurus nest. During the Jurassic period, rhynchocephalians could be found all over the world, came in all sorts of shapes and sizes, and were everything from aquatic fish hunters to bulky plant munchers. It is not still understood why, rhynchocephalians all-but disappeared, while snakes and lizards grew to be the more common and diverse reptiles across the globe.

More study of these specimens could reveal why just New Zealand’s tuatara is surviving today. “These animals may have disappeared partly because of competition from lizards but perhaps also due to global shifts in climate and changing habitats,” Carrano said. “It’s fascinating when you have the dominance of one group giving way to another group over evolutionary time, and we still need more evidence to explain exactly what happened, but fossils like this one are how we will put it together.”

[Related: Feast your eyes on exquisite fossils from an ancient rainforest (and more).]

This fossil is almost entirely complete, and is only missing the tail and parts of the hind legs. According to Carrano, such a complete skeleton is rare for small prehistoric creatures like this because, “their frail bones were often destroyed either before they fossilized or as they emerge from an eroding rock formation in the present day.” Paleontologists typically identify Rhynchocephalians from small fragments of their jaws and teeth.

The team used CT scans to capture everything they possibly could about the fossil and created a nearly complete 3D reconstruction of the animal. The 3D skull is of particular interest.

“Such a complete specimen has huge potential for making comparisons with fossils collected in the future and for identifying or reclassifying specimens already sitting in a museum drawer somewhere,” said research associate, David DeMar Jr., in a press release. “With the 3D models we have, at some point we could also do studies that use software to look at this critter’s jaw mechanics.”

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About 15 million years before the blockbuster hit “Jaws” snapped up the attention of generations of movie goers, the mightly megalodon (Otodus megalodon) stalked the Earth’s oceans. The ancestor of modern-day sharks could eat prey the size of an orca whale in only about five bites. The largest specimens reached between 58 and 72 feet long and had teeth that are almost three times the size of a modern-day great white.

Now, a team of researchers in southern Maryland have unearthed fossil evidence of a possible bottoms-up megalodon attack on a whale. The fossils were found close together in southern Maryland’s Calvert Cliffs, by Mike Ellwood, a Calvert Marine Museum volunteer and fossil collector. They date back to the Miocene Epoch (about 23 million to 5.3 million years ago), when Maryland was covered in a warm and shallow coastal sea with big plumes of sea algae and succulent aquatic plants that supported turtles, crustaceans, and marine mammals.

In an interview with Live Science, Stephen J. Godfrey, a curator of paleontology at the Calvert Marine Museum in Solomons, Maryland and lead author of the study said “in terms of the fossils we’ve seen on Calvert Cliffs, this kind of injury is exceedingly rare. The injury was so nasty, so clearly the result of serious trauma, that I wanted to know the backstory.”

[Related: 3D models show the megalodon was faster, fiercer than we ever thought.]

The study, published last month in the journal Palaeontologia Electronica, details their examination of two fossils from the whale’s fractured vertebrae and one megalodon tooth. They used CT scans and other medical imaging techniques at a local hospital to get a closer look inside the ancient remains.

One of the vertebrae shows evidence of a compression fracture. The study proposes that the whale’s backbone must have been forcefully bent into such a tight curve, that pressure from the vertebra right next to it smashed into one another to sustain this kind of injury.

“We only have circumstantial evidence, but it’s damning circumstantial evidence,” Godfrey told Live Science. “This is how we see the story unfolding. Although there are limitations to what we can claim, and we want the evidence to speak for itself.”

Another possible cause of this kind of injury to the backbone could be that the whale ingested a toxic algae that caused it convulse so violently that it broke its own back. The authors, however, argue that a megalodon attack is the most likely cause due to the magnitude of the injury to the spinal column bones.

The team also examined a megalodon tooth that was uncovered alongside vertebrae fossil. The tip of the tooth broke off, which could occur after it struck something hard like a bone. It also could have fallen out while swimming or feeding on an already dead or injured whale’s remains. But the team isn’t ruling out the possibility that a megalodon lost its tooth while ramming its jaws into a whale.

[Related: Megalodons liked to snack on sperm whale snouts.]

The teeth of extinct sharks are a common discovery in Calvert County Maryland and they come from a wide variety of shark species, according to the Maryland Geological Survey. Citizen scientists and paleontologists alike have uncovered teeth from Galeocerdo contortus and Galeocerdo triqueter (similar to modern day tiger sharks), Sphyrma prisca (a relative of the hammer head shark), and Odontaspis elegans (the Sand Shark). It’s thought that this area was a whale and dolphin calving ground, which potentially made the smaller whales easier targets for hungry megalodons.

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Late Permian Period reptile Coelurosauravus elivensis (C. elivensis) won’t be laying colorful scaly eggs or burning down armies anytime soon, but it does have the title of the planet’s first flying reptile.

In a new study published in Journal of Vertebrate Paleontology, researchers believe that the four-inch-long winged reptile evolved to glide between tree tops. C. elivensis was a tetrapod that lived during between 252 million to 260 million years ago in present-day Madagascar, and used a patagium (thin membranes extending from its torso to the front limbs) as a make shift pair of wings to travel above the tree canopy.

These unique features have earned the tiny lizard the title of “world’s first gliding reptile,” according to researchers from the French National Museum of Natural History in Paris and the Staatliches Museum für Naturkunde Karlsruhe in Karlsruhe, Germany. The first fossils of C. elivensis were unearthed in 1907 and sparked a spirited debate over how the reptile actually lived and how it evolved to have these wings. The team on this study created a near-perfect skeletal reconstruction of C. elivensis and the new research advanced knowledge of the tetrapod’s form and its habits. The team says that clues in the tree canopy of this extinct ecosystem have helped solve the puzzle.

[Related: Could dragons be real? Not in the way we think.]

A tree canopy of overlapping tree tops allowed the reptiles to move about without risking an altercation with predators on the ground.

“These dragons weren’t forged in mythological fire—they simply needed to get from place to place. As it turned out, gliding was the most efficient mode of transport and here, in this new study, we see how their morphology enabled this,” said lead author Valentin Buffa, from the Centre de Recherche en Paléontologie – Paris at the French Natural History Museum, in a press release.

The team looks at three known C. elivensis fossils and related specimens belonging to the Weigeltisauridae family of gliding Permian reptiles found present-day Germany. They focused on the postcranial portion (head skeleton), body, torso, limbs, and its “remarkable gliding apparatus,” called the patagium. The patagium is somewhat like a bat’s wing and is found in flying squirrels, sugar gliders, and colugos aka “flying lemurs.”

[Related: These flying squirrels fluoresce hot pink, and no one knows exactly why.]

Researchers were uncertain about the exact placement of the patagails (who together form the patagium) on C. elivensis‘ body and the study proposes that winglike structures were most likely located low on the trunk and extending from the dermal bones located between the sternum and pelvis or from the trunk’s musculature. This determination is based on the position of the bones, since none of the specimens contained any preserved soft tissues.

The team also compared this new location of these patagium to those of Draco. Draco (the Latin word for dragon) is a genus of modern-day gliding lizards often called “flying dragons.” These lizards predominantly live in Southeast Asia’s rainforests. The scientists reported that C. elivensis gliding apparatus was lower on its abdomen when compared to modern gliding lizards according to the statement and added that Draco’s patagials are supported by its long and flexible ribs.

“C. elivensis does bear a striking resemblance to the contemporary genus Draco,” Buffa said. “While its habits were likely similar to those of its modern counterpart, we do see subtle differences though. Like Draco lizards, Coelurosauravus was able to grasp its patagium with its front claws, stabilize it during flight, and even adjust it, allowing for greater maneuverability. An additional joint in one finger, though, may have enhanced this capability. This may have been a necessary compensation for the lower positioning of the patagium, which likely made it more unstable.”

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When looking at a map, the continents of South America and Africa look like they sort of fit together like puzzle pieces. This geographic symmetry is because the continents, and most of the land on Earth, were once fused together in a giant land mass called Pangea from about 200-300 million years ago. This ancient supercontinent influenced life on Earth during the Paleozoic and late Triassic periods. About 230 million years later, scientists have discovered Africa’s oldest dinosaur to date on the continent in Zimbabwe—and the nearly complete skeleton is now helping scientists better understand dinosaur evolution.

A nearly complete skeleton of Mbiresaurus raathi was discovered after five years, COVID-19 related delays, and extremely careful digging. Mbiresaurus lived along the banks of an ancient river in current day Zimbabwe, during the late Triassic period (about 252 million to 201 million years ago). The long-necked ancient lizard is a sauropodomorph, a relative of giant long-necked sauropods like Brachiosaurus and Apatosaurus. They were smaller than their late Jurassic to early Cretaceous counterparts, at about 6 feet long and 1.5 feet tall at the hip. By comparison, a later sauropod called Dreadnoughtus was about 85-feet-long.

According to the researchers, the Mbiresaurus was bipedal (stood on two legs), had a relatively small head, and it’s small, serrated, triangle-shaped teeth, suggesting that it was an herbivore or possibly omnivore.

“When we talk of the evolution of early dinosaurs, fossils from the Triassic age are rare,” said Darlington Munyikwa, the deputy director of National Museums and Monuments of Zimbabwe, who was part of the expeditions, in an interview with the BBC.

[Related: Were dinosaurs warm-blooded or cold-blooded? Maybe both.]

The findings were published yesterday in the journal Nature, and help answer why dinosaur fossils have only been found in some parts of Pangaea. Previously, the oldest known dinosaur specimens (dating back about 230 million years ago) were found in South America (specifically Argentina and Brazil), with a few partial specimens in India.

“The discovery of Mbiresaurus raathi fills in a critical geographic gap in the fossil record of the oldest dinosaurs and shows the power of hypothesis-driven fieldwork for testing predictions about the ancient past,” said primary author Christopher Griffin, who graduated in 2020 with a Ph.D. in geosciences from the Virginia Tech College of Science, in a press release. “These are Africa’s oldest-known definitive dinosaurs, roughly equivalent in age to the oldest dinosaurs found anywhere in the world.”

[Related: Move over, Stegosaurus, there’s a new armored dino in town.]

Griffin (now a postdoc at Yale University) Munyikwa, and Michel Zondo of the Natural History Museum of Zimbabwe in Bulawayo unearthed the nearly complete skeleton in the banks of the Cabora Bassa River Basin. In an interview with Science, Griffin recalled spotting what appeared to be a thigh bone sticking out of the river, “As soon as I dug that out, I knew that I was holding Africa’s oldest dinosaur,” said Griffin. “I had to sit down and breathe for a minute, because I thought, ‘There could be a lot more [bones] in there.’”

The new dinosaur received its name after Mbire, the the district in Zimbabwe where the skeleton was found and also is the name of an historic Shona dynasty that once ruled the region. The name “raathi” is in honor of Michael Raath, a paleontologist who first published the discovery of fossils in northern Zimbabwe.

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Fulfilling the dreams of child paleontologists everywhere, the skeletal remains of a possible sauropod, the group that includes the iconic brachiosaurus genus, have been found in a backyard. The 82-foot-long skeleton was uncovered in Pombal, a city in central Portugal.

In 2017, the property owner noticed some fragments of fossilized bones during a backyard construction project. The owner contacted a research team who investigated the site and launched an excavation campaign. Between August 1 and 10 of this year, Portuguese and Spanish paleontologists working on the site have unearthed what could be the remains of the largest sauropod dinosaur ever found in Europe.

[Related: This fossilized dinosaur embryo is curled up just like a baby bird.]

“It is not usual to find all the ribs of an animal like this, let alone in this position, maintaining their original anatomical position. This mode of preservation is relatively uncommon in the fossil record of dinosaurs, in particular sauropods, from the Portuguese Upper Jurassic”, said Elisabete Malafaia, Postdoctoral researcher at the Faculty of Sciences of the University of Lisbon (Ciências ULisboa), Portugal, in a press release.

Sauropods were long-necked, long-tailed, herbivorous dinosaurs that stood on four legs (or quadrupedal). The smallest sauropods stood at about 50 feet and the largest (Brachiosaurus) standing at an astounding 98 feet tall and weighed over 170,000 pounds.

Researchers have gathered an important set of axial skeleton parts from the site, including vertebrae and ribs of a possible brachiosaurid sauropod dinosaur. The Brachiosauridae group lived during the Upper Jurassic period to the Lower Cretaceous period, about 160 to 100 million years ago. Brachiosauridaes are characterized by their very developed forelimbs. Some of the most notable species in this group of sauropods, are  Brachiosaurus altithorax, Giraffatitan brancai, and Lusotitan atalaiensis (found in western Portugal). A leaf-munching, herd-moving brachiosaurus was also the first dinosaur spotted by famed fictional paleontologist Alan Grant, tenacious fictional paleobotanist Ellie Sattler, and witty fictional chaotician Ian Malcolm in 1993’s Jurassic Park.

[Related: The largest dinosaurs got huge way earlier than we thought.]

The team is now testing a hypothesis that there are more parts of the skeleton that could be uncovered at other deposit sites.

“The research in the Monte Agudo paleontological locality confirms that the region of Pombal has an important fossil record of Late Jurassic vertebrates, which in the last decades has provided the discovery of abundant materials very significant for the knowledge of the continental faunas that inhabited the Iberian Peninsula at about 145 million years ago”, adds Malafaia.

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When Africa and South America split apart during the Jurassic, birthing the Atlantic Ocean, the separation left a plateau of shallow ocean off the west coast of Guinea. “All the sediments are very flat, almost like a layer cake,” says Uisdean Nicholson, a marine geologist at Heriot-Watt University in Scotland who studies the region to learn about the birth of the Atlantic.

So in 2017, when Nicholson was examining seismic scans of the region taken by oil and gas exploration vessels, an unexpected feature jumped out: a 5-mile-wide dimple buried deep in the cake.

A closer analysis of the site, led by Nicholson and published today in the journal Science Advances, argues that it’s the crater from a meteor as wide as the Eiffel Tower is tall. If it’s confirmed as a crater, it would have crashed into Earth within a million years of the Chicxulub meteor that caused the extinction of the dinosaurs.

Nicholson hunted for other ways to explain the dimple—escaping methane bubbles, tectonic activity, or a volcano. But none of them quite explained the crater’s size, location, and shape.  So he turned to cosmic impact experts for help. “Probably every week, somebody sends me circles they spotted on Google Earth, or in seismic data,” says Sean Gulick, an expert in meteor strikes at the University of Texas Institute for Geophysics, and a coauthor on the research. But the dimple, which the team calls the Nadir Crater, passed the tests they threw at it. “Shapes, sizes, even modeling, it’s all fitting,” says Gulick.

To further confirm the explanation, Veronica Bray, a planetary scientist at the Lunar and Planetary Laboratory in Tucson and a member of the team, simulated multiple meteor strikes in different ocean depths. A rock longer than 1,000 feet across, striking the half-mile-deep ocean, created a close approximation to the actual crater. According to the simulation, in the first few seconds after the impact, the rock would have plunged nearly a mile into the ocean floor, vaporizing rocks and water, and sending a tsunami in all directions. 

The vibrations from the impact would be so intense that “the rocks or sediment below the seabed become a fluid,” Nicholson says. The rock around the crater would shatter, and “you get this massive vertical column, like you dropped something into a puddle,” he says. “That happens with the water, but it also happens with the rocks below”—leaving a crater with an uplifted mound of solid rock in the middle, like what’s buried under the Guinean seafloor.

“The energies involved in this are enormous,” says Gulick. “This is 1000 times the energy of the Tonga eruption. It would generate earthquakes that are magnitude 7.5 or 8.”

Ludovic Ferrière, an impact crater expert from the Natural History Museum Vienna who was not involved in the work, agrees that the shape of the feature is interesting and warrants further investigation—but he’s skeptical of the decision to publish on the basis of seismic images alone. “It’s a very nice proposal,” he says. “”But it’s too preliminary. At the end they may be right, but they may be completely wrong.”

[Related: This small asteroid has a tiny moon of its own]

Ferrière—who says that he discussed the crater with Gulick at a bar days before the publication—says that he has found similarly compelling craters.  But, without physical evidence, he doesn’t think they pass scientific scrutiny to publish. “To find the killer in a murder, you need DNA or blood,” he says. The same is true for an impact crater: The only hard evidence of a meteor are the presence of “shocked” minerals that form only under the hammer blow of a cosmic strike, or actual spray from the extraterrestrial object.

Drilling from a ship hundreds of feet into the seafloor itself is the only way to be sure. Yet this creates a chicken-egg problem. The International Ocean Discovery Program, the academic institution best equipped to take a sample—“at a cost of several million dollars,” Nicholson writes over email–would do so only after a peer-reviewed paper confirms that it is a good candidate. 

The International Ocean Discovery Program’s ship, which can collect core samples under thousands of feet of water and hundreds more feet of rock, will visit the region in 2023. The team has submitted an application for time with the drill, and hopes to analyze samples from the crater in the next few years. 

That drilling will also clarify the age of the proposed crater. Based on cores drilled a little over 100 miles from the proposed crater, the site sits right around the K-PG boundary, the line that marks the mass extinction of dinosaurs, pterosaurs, and giant marine reptiles, 65 million years ago. That die-off was caused when the miles-wide Chicxulub meteor smashed into what’s now the Yucatan Peninsula.

[Related: It was probably springtime when an asteroid did the dinosaurs in]

But the sound waves the team is relying on in Guinea produce a slightly fuzzy image, which can’t firmly pin down the date. “To the best of our knowledge, we’re at the boundary, but it could be, could be a million years older or younger,” says Nicholson.

If the crater sits right at the boundary, it’s possible that it was caused by a fragment of the Chixculub meteor that broke off on a previous fly-by past Earth, though Gulick thinks this is unlikely. Alternatively, it could have been  part of an asteroid swarm that intercepted our planet over the course of thousands of years. Ferrière, for his part, calls these hypotheses “speculation upon speculation”—without confirmation that the Nadir Crater is actually a crater, he says, “it’s like constructing a big castle of stone on something that is not stable.”

A similarly sized meteor hits Earth roughly every 700,000 years, so even if it’s a crater, it’s  not necessarily connected to the Chicxulub impact. But Gulick says that documented craters are so rare–there are just over 200 confirmed or likely craters on Earth—that to find one within a million years of Chicxulub would be a surprise.

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About 23 to 3.6 million years ago, a shark roughly three times the size of the great white shark (Carcharodon carcharias)—arguably made famous in the blockbuster 1975 movie JAWS—roamed the oceans of the world. The megalodon (Otodus megalodon or O.megalodon) is believed to be the largest shark that ever has lived, measuring 34 to 66 feet and weighed upwards of 100,000 pounds. That’s about the weight of a train car.

New research published this week in the journal Science Advances suggests that the sizable shark was not only the apex predator of its day, but a “transoceanic super-predator” that could travel thousands of miles across oceans on long migrations, even faster than modern-day sharks. The research by Swansea University PhD student Jack Cooper, shark expert Catalina Pimiento from the Paleontological Institute and Museum at the University of Zurich, and John Hutchinson from the Royal Veterinary College shows the sharks may have eaten meals that were the size of an orca whale, consumed in an about five or more bites.

The researchers used data from an O. megoladon fossil vertebral column, various teeth, and a chondrocranium from our friend the great white shark (its closest living relative) to build out the 3D model.

“The 3D modeling of O.megalodon was only possible thanks to a rare and exceptional vertebral column specimen from Belgium: 141 vertebrae from a single shark,” said Cooper, in an e-mail to Popular Science. “It’s a one of a kind specimen that may well hold the key to further discoveries on this giant shark, having mostly been in museum storage in Brussels since the 1860s.”

Professor Hutchinson added, “Computer modeling provides us with an unprecedented ability to use exceptionally well-preserved fossils to reconstruct the entire body of extinct animals, which in turn allows estimations of biological traits from the resulting geometry. Models of this nature represent a leap in knowledge of extinct super predators such as megalodon and can then be used as a basis for future reconstruction and further research.”

The 3D model allowed the team to figure out the shark’s length, volume, and gape size. These measurements, in turn, helped them calculate its body mass, inferring swimming speed, energetic demands, and stomach volume based on the relationship between these variables and body mass in living sharks. The newly calculated swimming speed means that the shark was potentially able to swim further distances than its competitors, increasing how quickly it could migrate and eat its way around the ocean, larger like marine mammals prey included.

“Megalodon’s large body size and potential energetic demands suggest that it would need/prefer highly caloric prey, like whales. Prey encounters relate with not only preference, but also prey availability and abundance,” Pimiento added.

It is a lack of abundance that potentially drove the megalodon into extinction, roughly 3.3 million years ago, during the Pliocene epoch. A 2016 study published in the Journal of Biogeography and authored by Pimento suggests that the megalodon’s demise came not from dramatic swings in the climate, but due to a decrease its primary food source at the time (baleen whales) and increase in other predatory sharks (the great white included) and whales in the Orcinius genus.

As the prehistoric ocean’s top predator and resident globetrotter, O. megalodon’s extinction would have post major changes on global nutrient transfer and ocean food webs throughout the world.

“The extinction of this iconic giant shark likely impacted global nutrient transport and released large cetaceans from a strong predatory pressure,” said Pimiento.

Correction (August 23, 2022): A previous version of this post stated that the megalodon weighed similarly to the Space Shuttle Endeavour. The Endeavour weighed around 4.4 million pounds fully loaded.

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Paleontologists in southern Argentina have recently discovered an adorable, five-foot-long armored dinosaur. The Jakapil kaniukura roamed the Earth during the hot and humid Cretaceous period roughly between 145.5 and 65.5 million years ago, and weighed 9 to 15 pounds–the size of the average domestic cat. 

The tiny dino’s fossilized remains were dug up during multiple digs over the over the past 10 years near a dam in Patagonia’s Río Negro province. The province is home to the La Buitrera palaeontological zone, a region well-known for the discovery of three complete southern raptors (Unenlagia) skeletons, herbivorous terrestrial crocodiles, the oldest found chelid turtles, and more.

Jakapil is part of the Thyreophoran dinosaur group that lived from the Jurassic period to the early Cretaceous period whose name means “shield bearer.” This feisty-looking group includes the bony backed, spiky tailed Stegosaurus and the tank-like Ankylosaurus. Like its prickly cousins, Jakapil had built in physical defenses, with rows of bony oval-shaped armor along its neck, back, and down to its tail.

[Related: This fossilized butthole gives us a rare window into dinosaur sex.]

“It bears unusual anatomical features showing that several traits traditionally associated with the heavy Cretaceous thyreophorans did not occur universally,” wrote the study’s authors, Facundo J. Riguetti, Sebastián Apesteguía, and Xabier Pereda-Suberbiola. “Jakapil also shows that early thyreophorans had a much broader geographic distribution than previously thought.”

The team published their findings in the journal Scientific Reports on August 11th. They first discovered Jakapil’s partial skeleton alongside 15 tooth fragments, which revealed that jakapil’s teeth were leaf-shaped like a modern-day iguana’s. 

According to lead paleontologist Sebastián Apesteguía, Jakapil marks the first-of-its-kind discovery of an armored dinosaur from the Cretaceous in South America. It also resembles a more primitive form of thyreophoran dinosaur that lived in the area significantly earlier. 

“Thyreophorans originated about 200 million years ago and rapidly evolved into various species distributed throughout the world,” Riguetti, first author of the work and a Conicet doctoral fellow at the Center for Biomedical, Environmental and Diagnostic Studies at Maimónides University said in a release. “However,of these early thyreophorans, the lineage represented by ‘Jakapil’ was the only one that lasted until at least 100 million years ago.”

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What do elephants, camels, and sauropod dinosaurs all have in common? Soft tissue pads beneath their heels support their enormous sizes and weights. A new study published in Science Advances found that sauropod dinosaurs were likely capable of evolving to heights up to 76 feet—almost as high as the White House—because their feet had cushions which helped their massive bodies move without crushing their foot bones.

The evolution of gigantic dinosaurs and how they carried their enormous stature has been a topic of debate among paleontologists for more than a century–that, until now, had no concrete answer. “What is exciting is that our research finally resolves this 120-year-old hypothesis by providing, for the first time, biomechanical evidence to show how gigantic sauropods could support their weight on land,” says Andréas Jannel, a research associate at The University of Queensland and lead author of the study. 

These gigantic plant-eating dinosaurs, iconic for their long necks and tails, roamed Earth in the Jurassic epoch as early as 201 million years ago. But it was not until 145 million years ago that they started evolving into bigger sizes—10 times the height of the modern-day African elephant. When paleontologists found the first sauropod tracks a century ago, Jannel says, the footprints seemed to show the animals were walking on heels. This led some paleontologists to speculate that giant dinosaurs had a kind of heel pad when walking—although there was no evidence to definitively support the theory. Hundred-year-old technology was unable to study soft tissue in fossils, which are rarely preserved in rock to begin with. 

[Related: Even dinosaurs couldn’t escape the sniffles]

Jannel and his co-authors created a new approach to study dinosaur foot anatomy that included the bones and soft tissue. Using fossil data from the Upper Triassic to the Upper Jurassic epoch, the researchers created 3D virtual models from five different sauropod species, which weighed between 1,984 to 74,957 pounds. They also created a model based on the foot of an existing African elephant. Virtually reconstructing the foot postures allowed them to track how the sauropods would walk on dry land with and without a soft tissue foot pad. 

Soft tissue pads underneath the heel were necessary for sauropod dinosaurs to walk without causing tissue damage or breaking any bones. Similar to elephants, the pad cushion directed the loads away from the bones.

Study author Olga Panagiotopoulou, a senior lecturer of anatomy and developmental biology at Monash University, says the idea of fleshy foot pads came from looking at the fat pads found in elephants, rhinoceroses, and other living giants. These animals evolved bottom cushions to serve as shock absorbers to redistribute the pressure on their feet. Panagiotopoulou says a 2011 study, which found that ancestral elephants evolved to have large foot fat pads as they grew in size, partly inspired their hypothesis that sauropods had similar structures to reduce the stress on their bones and avoid fractures.

[Related: Dinosaurs who stuck together, survived together]

Smaller members in the sauropod family, the scientists found, also shared their version of a cushy foot pad. Using the fossilized tracks of sauropod precursors known as Plateosaurus, the researchers created a reconstruction of their foot that had toes slightly raised off the ground with no heel pad. The results indicate there was no way the foot skeleton alone could support their weight without some form of additional padding. “Our work suggests that the presence of an incipient heel pad in sauropod precursors laid the foundations for the evolution of a more substantial structure,” says Jannel. 

Kimberley Chapelle, a Kalbfleisch postdoctoral fellow in the American Museum of Natural History’s Division of Paleontology who was not affiliated with the study, says before this paper, no other studies tested the theory of whether sauropods had fatty pads in their feet. “This provides yet another puzzle piece to how sauropod dinosaurs got so big.” Although Chapelle says her only reservation would be that, while the study methods were tested on a modern-day elephant, “it would have been useful to see what predictions the models made for other living animals that have fat pads such as camels and rhinos, as well as those who don’t.”

With evidence for fatty foot pads in sauropod dinosaurs, Panagiotopoulou says she is planning to investigate how exactly they distribute the stress of walking by studying the foot mechanics of elephants, rhinoceroses, and horses. 

Jannel, on the other hand, is working to expand the 3D computational models to an entire sauropod limb—complete with soft tissue such as muscles, which are also rarely preserved in fossils. “This research and methodology are relatively new in the field of paleontology,” he explains. “So stay tuned, because this has a lot of potential for more research in the future, not only in sauropods but also other dinosaurs and prehistoric animals!”

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It’s got to be out there. It doesn’t matter that Otodus megalodon has by all scientific accounts been extinct for more than 3 million years. The ongoing earthly presence of the enormous shark persists in our collective imagination thanks to rumors, legends, and summer B flicks.

Meg mythology often posits that the 50-foot predator has been hiding for epochs somewhere at the bottom of the ocean. It’s a notion that’s launched more than a few books and pseudo-docs, all hinging on the fact that most of the planet’s nether waters are unexplored—and therefore rife with primo dens for enigmatic beasts. But based on what we know of the biological adaptations required for life down below, not many animals could pull off a deep-sea disappearing act. If megalodon is still out there (and that’s a pretty big if), it’s not what it used to be.

Fossil shark teeth got people hooked on the Meg long before paleontology took off in the early 19th century, when scientists started cataloging fossils with gusto. In 1835, Swiss naturalist Louis Agassiz described triangular, finely serrated teeth, which had been found worldwide since antiquity, as belonging to a “megatooth” relative of the great white.

Discoveries around the world—in locations as diverse as Panama, Japan, Australia, and the southeastern United States—piled up over time, but one particular find raised the specter of a Meg still swimming in the deep. In 1875, during an expedition for the Royal Society of London, the HMS Challenger dredged up 4-inch-long teeth from a depth of 14,000 feet near Tahiti. In 1959, zoologist Wladimir Tschernezky, who made a hobby of researching “hidden animals” like Bigfoot, estimated the specimens were just 11,300 years old. Other scientists have since dismissed this dating, but unscrupulous documentarians and curious amateurs still highlight the research as a hint that Meg might persist.

Save for the outliers found by the Challenger, the megalodon’s fossil record indicates it was a shore-hugging creature, similar to its distant cousin the great white. “Remains generally come from coastal marine rock deposits formed in tropical-temperate areas,” says DePaul University shark researcher Kenshu Shimada. The species’s dietary habits further confirm a shallow lifestyle, with gnawed ancient whale bones showing Meg’s preference for marine mammals. These air breathers had to break through the surface for oxygen, so paleontologists expect megalodon, like them, hung out near the shore.

The exact combination of factors that pushed the ancient shark into extinction is still murky. We do know that shallower oceanic zones were undergoing dramatic changes around 3.5 million years ago, when the giant disappears from the fossil record. Water was growing cooler, making marine mammals less abundant, and the newly evolved great white may have served as a nimble competitor for resources. But there’s no way to prove definitively what did in the Meg.

The lack of certainty helps some maintain hope of finding one in the deep. Believers have at least one thing right: The bottom of the sea is an enigma. Even though satellites have mapped 100 percent of its floor, a low-resolution chart alone doesn’t give us great insight into what actually lives there, says Louisiana Universities Marine Consortium Executive Director Craig McClain, who specializes in cataloging oceanic systems. While the idea of a deep-dwelling ancient creature is highly improbable, he says, the sliver of possibility is still tempting. Less imposing critters have indeed shown up unexpectedly; in 1938 biologists identified a living coelacanth—a species of fish presumed extinct for about 65 million years.

If the megalodon were living in the dark, inky depths, though, it would have had to become a very different sort of creature—one we might not find nearly as cinematic. For one thing, Shimada says, its ravenous metabolism would need to fundamentally change. Preliminary geochemical analysis of isotopes in remains, which can help scientists estimate the body temperature of prehistoric organisms, indicates that megalodon was “warm-blooded” in the same sense as the great white. That predator’s active ocean cruising generates enough body heat to keep it toastier than surrounding seawater, an effort that burns through the equivalent of about six pounds of flesh a day. Meg may have weighed as much as three times more, and would have presumably required proportional grub. Yet animals near the ocean floor have to get by on teensy scraps, preying on the scant species that live there or hoovering up biological detritus that sinks down from carcasses above.

This scarcity of food tends to make organisms evolve small, efficient forms, making many low-living sharks relatively sluggish and slight. A megalodon living far enough down to evade human detection might now look something like a sleeper shark—a long, cigar-shaped animal that’s about as lively as it sounds—as opposed to a burly, toothy beast.

Yet even if Meg had assumed a slender and slow disguise, we’d probably have seen evidence of it by now. “Ocean giants that we do know about have global distributions,” McClain says. Even if we rarely spy creatures like giant squids, which live in the more forgiving upper ranges of what we’d call the deep sea, they leave markers of their existence strewn around the world in the form of carcasses (and bites taken out of unlucky critters). We’ve yet to spot any such refuse, if it even exists.

But these realities can’t extinguish the Meg’s enduring myth (and summer movie franchises). “As a deep-sea explorer and as a scientist who spends a lot of time researching known ocean giants, I really want there to be some unknown one that is undiscovered, and to make that discovery,” McClain says. Its mysterious nature—what we know of it comes largely from studying teeth—makes it enticing to imagine the Meg’s pulled off the ultimate vanishing act and could, perhaps, reemerge at any moment. The key is where scientists decide to look. While paleontologists are almost certain megalodon doesn’t swim in our modern seas, they might still find more details about the species in the depths of the fossil record—and its enduring secrets could break the surface when we least expect.

A history of the megalodon

16 million years ago – Otodus megalodon evolves from an ancestral group of megatooth sharks—the last member of a line that began 60 million years ago.

10 million years ago – The shark spreads to coastal waters worldwide. Clusters of baby teeth near Panama suggest nurseries were close to shore.

5 million years ago – Great white sharks evolve, and likely compete with the massive Meg to eat the same marine mammals, such as whales.

3.5 million years ago – Otodus megalodon seemingly goes extinct around a time of upheaval, including cooling seas and a dip in the species it munched on.

70 CE – Pliny the Elder notes that large “tongue stones” found in the rock strata of Europe may fall from the heavens during lunar eclipses.

1666 – Danish scientist Nicolas Steno dissects the head of a shark found off the coast of Italy and speculates that “tongue stones” are teeth.

1835 – Swiss naturalist Louis Agassiz coins the name Carcharodon megalodon in describing a set of the creature’s giant chompers.

1875 – The HMS Challenger dredges up megalodon teeth from the deep sea near Tahiti, fueling speculation about the shark’s survival.

1909 – Researchers build a model of a Meg jaw that fits six standing adults—suggesting an 80-foot body. This is now considered oversize.

1919 – Fishers in Australia claim to see a massive shark eat multiple lobster pots. The legend eventually makes its way into megalodon lore.

1974 – Peter Benchley publishes Jaws, which plays with the idea that a prehistoric man-eater might lurk in the deep. The public is hooked.

2016 – After decades of debate on the specifics of Meg’s family tree, the giant shark gets the new scientific name Otodus megalodon.

This story appears in the Fall 2020, Mysteries issue of Popular Science.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

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When the first dinosaur fossils were recognized in the mid-19th century, scientists envisioned that the creatures were basically giant, lumbering lizards. They also presumed that dinosaurs were like present-day, cold-blooded lizards, meaning that their body temperature depended on the surrounding environment. However, this notion was later fiercely debated.  

“The general picture that we have of dinosaur physiology has changed quite a bit through the last [several] decades,” says Jasmina Wiemann, a molecular paleobiologist at the California Institute of Technology. “Our understanding of what dinosaurs looked like and lived like is directly related to the question of whether they were cold-blooded, warm-blooded, or somewhere in between.” 

A new analysis published by Wiemann and her collaborators on May 25 in Nature indicates that the ancestors of dinosaurs were warm-blooded, or capable of maintaining a constant internal temperature. The researchers used a new technique to estimate the metabolic rates of modern and extinct animals based on the molecular composition of their bones. They concluded that many iconic dinosaurs such as Tyrannosaurus rex and the giant sauropods were warm-blooded, but cold-bloodedness later emerged in some dinosaurs such as Stegosaurus. 

Enrico Rezende, an evolutionary biologist at Pontifical Catholic University of Chile who has studied the evolution of warm-bloodedness, or endothermy, calls the findings “quite impressive.”

The results are “not entirely surprising, but it’s definitely good to have some estimate of metabolic levels,” he says, explaining that it breaks away from rigidly categorizing dinosaurs as warm-blooded or cold-blooded. “Essentially what this shows is that we have this whole gradient of metabolic levels.” 

Modern lizards or crocodiles must bask in the sun to raise their body temperature, while warm-blooded animals such as birds and mammals don’t need to do this. Being endothermic could have allowed dinosaurs to be more active and range over larger areas, Rezende says. They would also be less vulnerable to chilly temperatures, which means they could be more active at night and would fare better on elevated terrain or at high latitudes. On the other hand, warm-blooded dinosaurs would require a lot of energy to fuel their high metabolisms, which means they would need to spend a lot of time feeding.

“Understanding the metabolic levels would tell us quite a lot about how they could interact and how these ecosystems could be built,” Rezende says.

[Related: Spinosaurus bones hint that the spiny dinosaurs enjoyed water sports]

Researchers have used various procedures to explore the extent to which dinosaurs were able to generate their own heat, says Lucas Legendre, a paleontologist at the University of Texas at Austin. One line of evidence comes from body temperature estimates based on temperature-sensitive minerals preserved in fossils. Other researchers study the growth rings in dinosaur thighbones to gauge how fast the animals grew. Legendre and his colleagues have also used blood vessel and bone cell size to infer that carnivorous dinosaurs had high metabolic rates close to those of today’s birds. 

The Nature paper indicates that, in terms of physiology, dinosaurs typically had more in common with their closest living relatives—birds—than with lizards, Legendre says. “This is a new piece of evidence that confirms what a lot of researchers have been saying for the past decade,” he says. 

For the new work, the researchers took a more direct approach than earlier investigations, says Matteo Fabbri, a paleontologist at the Field Museum of Natural History in Chicago and coauthor of the study. The team examined byproducts of metabolism—the process by which animals convert nutrients and oxygen into energy—preserved in newly-formed as well as fossilized thighbones. 

“It is the metabolism that determines whether a lot of excess heat is generated as part of the breathing process and whether an animal is cold-blooded or warm-blooded,” Wiemann says.

During this process, chemicals called reactive oxygen species form and generate molecules called advanced lipoxidation end-products. These leftovers build up and “leave a fingerprint in pretty much every tissue,” Rezende says. An animal with a high metabolic rate uses more oxygen than one with a low metabolic rate, so it should have higher levels of these compounds in its body. 

Wiemann and her team scanned the bones of 30 fossilized animals and 25 modern birds, mammals, and reptiles using techniques called Raman and Fourier-transform infrared spectroscopy. This allowed them to measure the accumulated amounts of advanced lipoxidation end-products. 

“We basically use these data to infer the evolution of metabolism,” Wiemann says. “What we figured out is that dinosaurs were ancestrally warm-blooded.”

[Related: The fiery end of the dinosaurs kicked off the golden age of mammals]

The findings indicate that endothermy independently evolved in the group encompassing dinosaurs and the flying reptiles known as pterosaurs, in mammals, and in marine reptiles known as plesiosaurs. The researchers calculated particularly high metabolic rates for a long-necked diplodocid, Allosaurus, and birds, while T-rex had a somewhat lower metabolic rate than other carnivorous theropod dinosaurs. Strikingly, several of their more distant relatives had metabolic rates on par with modern lizards, indicating they were cold-blooded, or ectothermic. These included Stegosaurus, Triceratops, and a duck-billed hadrosaur.

“That is quite fascinating because it means the range of metabolisms realized in dinosaurs is a lot broader than originally thought,” Wiemann says. “That brings up interesting questions as to what triggers the evolutionary increase or decrease in the metabolic rate, and what does this mean for the lifestyles of the animals?”

Researchers have previously suggested that warm-bloodedness helped prehistoric birds and mammals adapt during the mass extinction that killed off the rest of the dinosaurs about 66 million years ago. However, the evidence that many Late Cretaceous dinosaurs had high metabolic rates hints that other traits such as body size were probably key to the survivors’ success, Wiemann says.  

The findings will need to be verified with further analyses that include more extinct animals, Legendre says. Still, the metabolic byproducts Wiemann and her team probed offer a source of data that researchers can compare with other traits.

“The fact that they used this new method adds one additional piece of the puzzle,” Legendre says. “Hopefully we’ll be able in the next few years to come up with a more precise picture of how dinosaurs and their close relatives were able to produce metabolic heat.”

Updated (May 26, 2022): The headline of this story has been updated to better reflect the research study’s question and the debate about dinosaur endothermy.

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Excerpted from The Last Days of the Dinosaurs by Riley Black. Copyright © 2022 by Riley Black and reprinted by permission of St. Martin’s Publishing Group.

Picture yourself in the Cretaceous period. It’s a day like most any other, a sunny afternoon in the Hell Creek of ancient Montana about 66 million years ago. The ground is a bit mushy, a fetid muck saturated from recent rains that caused a nearby floodplain stream to overrun its banks. If you didn’t know any better, you might think you were wading on the edge of a Gulf Coast swamp on a midsummer day. Magnolias and dogwoods shoulder their way into stands of conifers, ferns, and other low-lying plants gently waving in the light breeze drifting over the open ground you now stand upon. But a familiar face soon reminds you that this is a different time.

A Triceratops horridus ambles along the edge of the forest, three-foot-long brow horns slightly swaying to and fro as the pudgy dinosaur shuffles its scaly, ten-ton bulk over the damp earth. The dinosaur is a massive quadruped, seemingly a big, tough-skinned platform meant to support a massive head decorated with a shield-like frill jutting from the back of the skull, a long horn over each eye, a short nose horn, and a parrot-like beak great for snipping vegetation that is ground to messy pulp by the plant-eater’s cheek teeth. The massive herbivore snorts, making some unseen mammal chitter and scramble in alarm somewhere in the shaded depths of the woods. At this time of the day, with the sun still high and temperatures above 80 degrees, there’s barely another dinosaur in sight—the only other “terrible lizards” plainly in view are a couple of birds perched on a gnarled branch peeking out from just inside the shadow of the forest. The avians seem to grin, their tiny insect-snatching teeth jutting from their beaks.

This is where we’ll watch the Age of Dinosaurs come crashing to a fiery close.

In a matter of hours, everything before us will be wiped away. Lush verdure will be replaced with fire. Sunny skies will grow dark with soot. Carpets of vegetation will be reduced to ash. Contorted carcasses, dappled with cracked skin, will soon dot the razed landscape. Tyrannosaurus rex—the tyrant king—will be toppled from their throne, along with every other species of non-avian dinosaur no matter their size, diet, or disposition. After more than 150 million years of shaping the world’s ecosystems and diversifying into an unparalleled saurian menagerie, the terrible lizards will come within a feather’s breadth of total annihilation.

We know the birds survive, and even thrive, in the aftermath of what’s to come. A small flock of avian species will carry on their family’s banner, perched to begin a new chapter of the dinosaurian story that will unfold through tens of millions of years to our modern era. But our favorite dinosaurs in all their toothy, spiked, horned, and clawed glory will vanish in the blink of an eye, leaving behind scraps of skin, feather, and bone that we’ll unearth eons later as the only clues to let us know that such fantastic reptiles ever existed. Through such unlikely and delicate preservation our favorite dinosaurs will become creatures that defy tense—their remains still with us, but stripped of their vitality, simultaneously existing in the present and the past.

The non-avian dinosaurs won’t be the only creatures to be so harshly cut back. The great, batwinged pterosaurs, some with the same stature as a giraffe, will die. Fliers like Quetzalcoatlus, with a wingspan wider than a Cessna and capable of circumnavigating the globe, will disappear just as quickly as the non-avian dinosaurs. In the seas, the quad-paddled, long-necked plesiosaurs and the Komodo dragon cousins called mosasaurs will go extinct, as well as invertebrates like the coil-shelled squid cousins, the ammonites, and flat, reef-building clams bigger than a toilet seat. The diminutive and unprepossessing won’t get a pass either. Even among the surviving families of the Cretaceous world, there will be dramatic losses. Marsupial mammals will almost be wiped out in North America, with lizards, snakes, and birds all suffering their own decimation, too. Creatures of the freshwater rivers and ponds will be among the few to get any sort of reprieve. Crocodiles, strange reptilian crocodile mimics called champsosaurs, fish, turtles, and amphibians will be far more resilient in the face of the impending disaster, their lives spared by literal inches.

[Related: If that asteroid had been 30 seconds late, dinosaurs might rule the world and humans probably wouldn’t exist]

We know the ecological murder weapon behind this Cretaceous case study. An asteroid or similar body of space rock some seven miles across slammed into Earth, leaving a geologic wound over fifty miles in diameter. Most species from the Cretaceous disappeared in the aftermath. It’s difficult to stress the point strongly enough. The loss of the dinosaurs was just the tip of the ecological iceberg. Virtually no environment was left untouched by the extinction, an event so severe that the oceans themselves almost reverted to a soup of single-celled organisms.

But the reason we’ve gone back to this place and this one infamous moment is to understand not only why there are no Ankylosaurus descendants at the zoo but also how and why we came to exist. The Age of Mammals, a marker literally set down in stone, would never have dawned if this impact hadn’t allowed for evolutionary opportunities that were closed for the previous 100 million years. The history of life on Earth was irrevocably changed according to a simple phenomenon called contingency.  If the asteroid’s arrival had been canceled or significantly delayed, or if it had landed on a different place on the planet, what transpired during the millions of years that followed the strike would have unfolded according to an altered script. Perhaps the non-avian dinosaurs would have continued to dominate the planet. Maybe marsupials would have held sway as the most common beasts. Perhaps some other disaster, like massive volcanic eruptions in ancient India that picked up around the same time, would have sparked a different sort of extinction. It’s likely that the Age of Reptiles would have marched on unimpeded, but without the origin of any species introspective enough to engage in such ruminations about time and its flow. This day was as critical for us as it was for the dinosaurs.

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More than 90 million years ago, a dinosaur similar in size to T. rex cruised through shallow waters in search of prey, scientists reported today in the journal Nature. 

A number of ancient reptiles such as plesiosaurs and ichthyosaurs are known to have had marine lifestyles, but dinosaurs have generally been considered landlubbers. However, an analysis of the density of 380 bones belonging to a variety of dinosaurs, other extinct creatures, and present-day animals suggests that the iconic Cretaceous dinosaur Spinosaurus and one of its close relatives were capable swimmers. 

Based on the new findings and other reports, it’s “strongly plausible” that Spinosaurus was an aquatic dinosaur, says Alexandra Houssaye, a paleontologist at the French National Natural History Museum in Paris who wasn’t involved in the research.

While Spinosaurus probably didn’t have the agility or diving abilities seen in today’s seals or dolphins, its bones suggest the enormous predator was more comfortable in water than on land and may have swam along the riverbed like a misshapen hippopotamus or crocodile, Houssaye says.

[Related: Most dinosaurs didn’t swim—but this ‘dino equivalent of Jaws’ sure did]

Spinosaurus belongs to a family of meat-eating dinosaurs known as spinosaurids that emerged during the Jurassic Period. They had narrow, crocodile-like faces and long spines along their backs that could grow to around 6 feet tall, says Matteo Fabbri, a paleontologist at the Field Museum of Natural History in Chicago and coauthor of the study. Although Spinosaurus wasn’t quite as heavy as T. rex, it was longer, with some specimens reaching an estimated 50 feet. 

The first Spinosaurus fossil was discovered in Egypt in the early 20th Century but was destroyed during World War II. During the 1980s and 1990s, researchers began to find fragmented fossils from Spinosaurus and its family members around the globe and surmised that spinosaurids were mostly land dwellers that sometimes waded through the water in search of fish, similar to present-day herons. 

Then in 2014, a Spinosaurus skeleton in unusually good condition was identified in Morocco. “It’s created a huge debate in the field of paleontology,” Fabbri says. He and his collaborators noted a number of traits, including stubby hindlimbs and paddle-like feet, that hinted that the dinosaur was at least partly aquatic. In 2020, the team reported that Spinosaurus’s tail had an unusual fin-like shape that could have propelled it through the water similarly to the tails of modern crocodiles. 

Still, Fabbri says, it can be difficult to judge how much time an animal spent underwater by the shape of its bones. Today’s whales and seals have plenty of skeletal characteristics that reveal their aquatic tendencies. But in other water-loving species, such as hippos and tapirs, these features aren’t as obvious. 

Even though they have a well-documented aquatic lifestyle, “if you look at skeletons of hippos they look much more like terrestrial animals than anything else,” Fabbri says. “So is it possible that maybe we’re underestimating the ecological diversity of the fossil record because we are only focusing on anatomy?”

To address this question, he and his colleagues measured the bone density of Spinosaurus and two other spinosaurids, Baryonyx and Suchomimus, and compared them to other dinosaurs and extinct reptiles, Cretaceous birds, as well as a wide array of modern birds, mammals, and reptiles. The researchers examined the thighbones and ribs of their specimens using CT scanning and by examining thin slices of bone under the microscope.

“Higher density means there’s more tissue per single volumetric unit,” Fabbri says. “If you are an aquatic animal…if you are denser you can sink easily, and therefore you have more buoyancy control.”

Animals that submerge themselves underwater, such as hippos, manatees, crocodilians, and penguins, have denser bones than terrestrial animals and aquatic animals that dive deeply to search for food, including ichthyosaurs and modern whales and seals. These more active swimmers rely on their own movements, rather than bulky bones, to control their buoyancy, Houssaye says. When land-dwelling animals such as the ancestors of today’s whales take to the water, dense bones evolve early in the transition. “​​The inner structure changes more quickly than the shape of the bones,” she says.

Fabbri and his team observed that generally an animal’s bone density was mostly unrelated to its body size. They also noted that flying animals were somewhat more likely to have lightweight bones, and the densest bones were found among aquatic animals. In shallow-water specialists, he says, “You don’t have this donut-shaped cross section where you have bone outside and emptiness in the middle; you simply have a lot of bone that reaches to the center.”

The researchers found that both Spinosaurus and Baryonyx had extremely dense bones, similar to penguins, cormorants, and plesiosaurs. They may have returned to land to lay their eggs, Fabbri says, but probably spent most of their time in the water. 

[Related: These ancient, swimming reptiles may have been the biggest animals of all time]

On the other hand, Suchomimus had bones more similar to the other dinosaurs included in the analysis, suggesting it didn’t hunt underwater like its cousins. However, Suchomimus’s elongated snout and cone-shaped teeth suggest that it did feed on fish, and may have waded along riverbanks. 

Most dinosaurs probably weren’t built for living in the water, Fabbri says. Nonetheless, there may be other extinct animals who were better suited for swimming than scientists have previously assumed based on the shape of their bones. The next step, he says, is to measure the bone density of a broader array of dinosaur fossils.

“The fossil record is pretty patchy, meaning that a majority of skeletons are very fragmentary,” Fabbri says. “So this was very exciting because it was a way to say, okay not only can we understand the ecological adaptations in the fossil record, but you don’t need a full skeleton to understand it.”

One limitation of the analysis is that very compact ribs are sometimes seen in land animals, Houssaye notes, so these bones aren’t necessarily indicative of an aquatic lifestyle. Still, the densely-packed thighbones Fabbri and his colleagues observed in Spinosaurus do suggest that these dinosaurs were water dwellers. In the future, she says, researchers may find more evidence for Spinosaurus’s aquatic nature by examining the density of additional bones such as the forelimbs and investigating whether density is consistent throughout the length of the bones.  

“Because there are not many bones, we need to exploit them as much as possible,” she says.

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Tyrannosaurus rex, whose name translates to the tyrant lizard king, has long charmed the public as the star dinosaur in the Jurassic Park series. But the scene-stealing dino is stealing the spotlight again—this time, in a drama over how it should be classified. A controversial new study published in the journal Evolutionary Biology suggests that there may not just be one species in the Tyrannosaurus monarchy, but three, with T. regina and T. imperator as the long-lost cousins of T. rex. 

All hail the king (rex), queen (regina), and emperor (imperator) of the prehistoric kingdom? Not so fast, say other researchers, who argue would-be differences in the fossil specimens are too minor to support such a dramatic rift. 

To divide an extinct organism into species A, B, and maybe even C, there needs to be “enough separation” between the groups in the fossil record, says Ashley Poust, a paleontologist at the San Diego Natural History Museum who wasn’t involved in the study. He calls it “one of the biggest problems” of species identifications that only rely on what the eyes can discern.

Tyrannosaurus rex dominated the food chain in Northern America from 68 million to 66 million years ago. Over its two-million-year reign, members of the Tyrannosaurus genus could have spun off into several species, says Paul Sereno, a paleontologist at the University of Chicago who also wasn’t involved in the study. Just like the assortment of today’s predators roaming the African Serengeti, from lions to cheetahs to leopards, the top carnivores of the late Cretaceous period could have similarly diverged. 

“It’s difficult to believe that one species could [have lasted] millions of years across that expansive territory, with the amazing amount of herbivores that were out there to be eaten,” says Sereno. 

[Related: It was probably springtime when an asteroid did the dinosaurs in]

The study authors use two skeletal features, the stockiness of the femur and the number of teeth, to argue that T. rex should be redefined as three species. They recorded the length and diameter of thigh bones from 37 specimens. With their data, they gleaned that some Tyrannosaurs could be of a chunkier variety with a more robust femur. Or, the dinosaurs could have slender builds, as suggested by slimmer bones.  

Moreover, the researchers propose that different Tyrannosaurus species could either have one or two incisors per skull—the sharp tooth adapted for ripping into flesh. The collaborators named the stockier, double-incisor carnivore T. imperator. Another hunky species with one incisor remained T. rex. Finally, they called the single-incisored, svelte dinosaur T. regina. 

“This is a fairly subtle example of evolution [and] speciation,” says study author Gregory Paul, a freelance paleontologist. He thinks that as new Tyrannosaurus fossils are discovered, the larger sample size might allow researchers to run statistical analyses to unearth fresher findings about the tyrannical beasts. “Science is not dogmatic,” he adds, and what the world knows about the prehistoric lizard monarchy “is not set in stone.” 

But two bodily features aren’t enough to tell different species apart, says Thomas Carr, a vertebrate paleontologist at Carthage College in Kenosha, Wisconsin, who didn’t participate in the study. Carr previously analyzed 1,850 attributes of Tyrannosaurus fossils, and concluded that the dinosaur should remain under one species. There was no meaningful clustering among the attributes to bifurcate T. rex into multiple species. If a checklist of nearly 2,000 traits can’t justify the existence of T. rex‘s long-lost cousins, two indefinite patterns just won’t cut it, says Carr. 

“The features that identify species are utterly unique, smack-in-the-face-with-a-frying-pan obvious,” he notes. He thinks that femur size and incisor number shouldn’t qualify, given that the study couldn’t identify a quarter of the Tyrannosaurus specimens using the same metrics, despite the nearly perfect conditions of their skulls. 

Any differences perceived in this study can be chalked up to variation among individuals within a species, Carr adds, like how Homo sapiens can come in different shapes, sizes, and skin tones. 

[Related: How do we know what dinosaurs looked like?]

Other experts agree that the two features selected in the study aren’t distinct enough to diagnose different species. Jingmai O’Connor, an associate curator of fossil reptiles at the Field Museum of Natural History, Chicago, has a bone to pick with the vaguely descriptive terms peppered throughout the paper, including qualifiers such as “generally” and “usually.” She says such analysis might be “arbitrarily drawing the line in all the variation” when the disparities between the three supposed groups aren’t clear-cut at all. 

The Field Museum houses Sue, the world’s most complete T. rex skeleton and possibly one of the biggest. For now, Sue will keep its designation of king, despite the study suggesting its reclassification to the rank of emperor. 

It’s plausible that there were multiple species of Tyrannosaurus during their heyday, says Poust from the San Diego Natural History Museum. But he also thinks that the study’s fossil evidence might be insufficient to back the claim up and warrant the naming of new dinosaurs. “[The authors] look at species in a way that’s a little unclear,” he says. “If I went to the field and I dug up a Tyrannosaurus skeleton and looked at it, could I really easily tell which of these species it’s in?” 

Results aside, Carr of Carthage College is also concerned that half of the specimens in the new research are privately owned Tyrannosaurus fossils, which is a violation of the ethical standards of the Society of Vertebrate Paleontology. Relics from private collections aren’t necessarily accessible to all those who want to analyze them, so studies that use them might not be reproducible and verified by other experts.

Among the specimens in the Evolutionary Biology study is the near-complete fossil Stan, which was auctioned off to an anonymous bidder for a record-breaking $31.8 million last October. Since then, paleontologists have feared that the T. rex specimen, whose whereabouts are now unknown, might be lost to science forever. “I wouldn’t touch that stuff with a 10-foot pole,” says Carr. “We have to stick with museum and university collections that are there to provide fossils for study for all time.” 

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The dinosaur-killing asteroid that smashed into present-day Mexico 66 million years ago arrived in springtime, a new analysis suggests.

Scientists examined fossilized fish that perished shortly after the impact and used the growth patterns and chemicals preserved within the bones to pin down the timing of the event. The researchers concluded that the asteroid strike occurred during spring in the Northern Hemisphere, a time when many animals would have been raising young and especially vulnerable to the cataclysm. The season in which the asteroid made contact likely influenced which species survived the mass extinction that followed, the team reported on February 23 in Nature.

“The results of this study may help explain why some organisms went extinct at the end of the Cretaceous while others weathered the catastrophe,” Michael Donovan, a paleobiologist at the Cleveland Museum of Natural History who wasn’t involved in the research, said in an email. 

The asteroid’s immediate aftermath included forest fires, tsunamis, and rocky fallout that reached areas more than 2,000 miles from the Chicxulub impact crater in Mexico’s Yucatán Peninsula. One site that preserves evidence of these disturbances is the Tanis event deposit, which lies within the fossil-rich Hell Creek Formation in North Dakota.

Within tens of minutes after the asteroid impact, a seismic shockwave would have shaken the Tanis river and created a surge of water that hurled fish, ammonites, and other marine creatures ashore. Meanwhile, fragments of molten and vaporized rock called spherules, which were blasted into the atmosphere and resolidified, rained down upon the unfortunate animals as they were buried alive. 

“The shockwave moves very fast through the Earth’s crust and causes huge waves in the overlying bodies of water (lakes, rivers); very similar to a pool during an earthquake,” Melanie During, a PhD student in vertebrate paleontology at Uppsala University in Sweden and coauthor of the findings, said in an email.

To determine when this turmoil took place, During and her collaborators examined filter-feeding paddlefishes and sturgeons found in the deposit with spherules caught in their gills. Micro-CT scans of one of the skeletons revealed that the rock fragments hadn’t yet reached the digestive tract, confirming that the fish died very soon after impact. 

The researchers also peered at fine slices of the fishes’ fin spines and jawbones under the microscope. These bones grow similarly to trees, During said, adding a new layer every year. 

She and her team observed the tiny pores in each layer that once housed bone cells, which grow in size and density during the warm months when food is plentiful. “[We] saw that all these fishes recorded seasonality and died exactly at the same time: Spring,” During said.

The researchers next analyzed how the different types of carbon atoms, or isotopes, in the growth rings varied throughout the year. The fish receive “heavier” carbon isotopes from tiny creatures called zooplankton they dine on. When the fish died, the ratio of heavy carbon isotopes to lighter ones was increasing but hadn’t quite reached its typical summertime peak. This provided another piece of evidence that the fish met their end during the spring. 

“The actual extinction took far longer than just this moment itself,” During acknowledged. But the catastrophic season—spring in the Northern Hemisphere, and fall in the Southern one—would have eliminated many organisms even before the asteroid’s fallout enveloped Earth in nuclear winter, she said.

For many organisms, spring is the prime season for growth and reproduction after the harsh winter months, During said. As a result, the effects of the environmental devastation that followed in the asteroid’s wake may have been magnified for life in the Northern Hemisphere, Donovan added. 

Plants and animals in the Southern Hemisphere, which was in the midst of autumn, might have fared better; the asteroid arrived at a time when mammals were preparing to hibernate in burrows and insect pupae and dormant seeds were tucked away in the soil. 

[Related: June was probably a terrible month to be a dinosaur. Here’s how we know.]

Donovan and other researchers have previously reported that ecosystems in the Southern Hemisphere may have recovered more quickly from the mass extinction unleashed by the asteroid than Northern ecosystems. The new study may help explain the difference, he said, although many questions about this harrowing period remain.

“Were differences in regional recovery patterns a result of the distance from the asteroid impact site, variation in local climates, the season during which the impact occurred, or some combination?” Donovan said.

As researchers continue to investigate how the extinction that wiped out the dinosaurs unfolded across the planet, During said, one challenge is the relative scarcity in data from the Southern Hemisphere.  

There has been a “tremendous bias” toward studying this event from fossil finds in the Northern Hemisphere, with many more gaps in Southern Hemisphere data, During said. “It is absolutely worth it to concentrate on extracting more fossils from the Southern Hemisphere,” she said, “and doing so by including and supporting the local researchers who often lack funding to do their research.”

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Around 150 million years ago, a long-necked dinosaur in southwest Montana became very ill. The unfortunate sauropod might have endured a sore throat, headaches, and difficulty breathing. 

Although the dinosaur in question is long dead, signs of this sickness are preserved in its neck bones as lumpy growths. These abnormal structures may have been caused by a fungal infection similar to those seen in birds today, a team of paleontologists, veterinarians, and other anatomy specialists have determined. The growths represent the first evidence of a dinosaur respiratory infection and could shed light on certain aspects of dinosaur physiology, the team concluded on February 10 in Scientific Reports.

“I’ve looked at sauropods from all over the world and I’ve never seen a feature like this before,” says Cary Woodruff, the director of paleontology at the Great Plains Dinosaur Museum in Malta, Montana and a couthor of the findings. “It helps us understand the world that these dinosaurs were in—what kinds of illness and diseases plagued the tyrant lizards.”

Many of the ailments that struck dinosaurs are likely to remain a mystery because they left no trace on the bones. However, paleontologists have found fossil evidence of a host of maladies ranging from tooth infections to broken bones, arthritis, and cancer.

The dinosaur that Woodruff and his team examined was originally discovered in 1990 and nicknamed “Dolly” in honor of Dolly Parton. The fossil is similar in appearance to diplodocus, another long-necked herbivore that lived during the Late Jurassic. Dolly was probably between 15 and 20 years old when it died and reached a length of around 60 feet.

[Related: Duck-billed dinosaurs had the same bone tumors as people]

When Woodruff and his colleagues examined Dolly’s vertebrae, they noticed something odd.

Dinosaurs share numerous anatomical features with their living avian relatives and are thought to have breathed similarly to birds, he says. The respiratory system is more efficient in birds than mammals, with extra air sacs in the lungs and structures that penetrate into the bones. Dinosaurs also have sockets where respiratory tissue connects to the bone known as pleurocoels. “I like the analogy of a vacuum cleaner,” Woodruff says. “The respiratory tissue is like the hose, the bone is like the vacuum canister, and where that hose joins into the vacuum is the pleurocoel.”

Normally the bone in this region is very smooth. But in Dolly, the edges of pleurocoels on both the left and right sides of multiple vertebrae were knobbly and rough—a bit like a fossilized piece of broccoli. “Sticking out of it was this really gnarly, lumpy, irregular abnormal bone growth,” Woodruff says. “That was the smoking gun that this is not normal.”

To understand what might have caused the growths, he and his team searched for similar disorders among Dolly’s closest living relatives: birds and crocodilians. In crocodilians, the respiratory tract is “not as developed” as in birds, Woodruff says, and the respiratory tissue doesn’t pervade the bones. However, birds can develop respiratory infections that spread to the bone in the same location as Dolly’s lesions. 

To narrow down the type of infection Dolly suffered from, the researchers took CT scans of the afflicted vertebrae. In modern birds, some respiratory illnesses cause rind-like growths to develop on the outside of the bone. But in Dolly, the scans suggested, the interior of the bones was also “really screwed up,” Woodruff says. 

Unsurprisingly, no present-day ailments offered a perfect match for the ancient reptile’s growths. However, Dolly’s condition was most consistent with a very common infection called aspergillosis, which develops when birds, and humans, breathe in certain fungal spores. 

By the time such infections reach the bone, they’ve already had plenty of time to wreak havoc on the lungs and associated tissues. Birds with aspergillosis often cough, develop fevers, and lose weight. If a sick bird doesn’t receive treatment, the disease can lead to deadly pneumonia, much as COVID-19 does in people. 

All in all, Dolly would have felt pretty crummy. 

“We can’t say if Dolly just keeled over because of this disease, or just being so visibly sick or on its own from the herd was an easy target for predators,” Woodruff says. “But we can say in one way or another it ultimately caused the death of this animal.”

While Dolly probably didn’t have quite the same disease seen in today’s birds, its bony growths support the idea that dinosaurs were susceptible to fungal respiratory infections and may offer insights about how their immune systems worked. “Mammals and birds have very different immune systems, so if we have this non-bird dinosaur that was breathing like birds and has a bird-like respiratory infection, odds are its immunological response was much more like a bird than mammals or other reptiles,” Woodruff says.

The findings open up a “whole new dimension” in our understanding of dinosaur diseases, while providing a new insight into the musculoskeletal system of sauropods, says Ali Nabavizadeh, a comparative anatomist and paleobiologist at the University of Pennsylvania School of Veterinary Medicine who wasn’t involved with the research. Dolly’s infection also reinforces connections between dinosaurs and modern bird anatomy.

“This paper provides yet another piece of evidence to show just how modern dinosaurs—the birds—are biologically so similar to their extinct non-avian dinosaurian relatives, even to the point of showing similar diseases,” he said in an email. 

In the future, searching for similar lesions in sauropod vertebrae in collections around the world might reveal how prevalent respiratory infections were in these dinosaurs, Nabavizadeh said.

“I am excited to see how these findings can improve upon our knowledge of respiration as well as circulation in these breathtakingly enormous creatures.”

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Michael J. Benton is a professor of Paleobiology, University of Bristol. This story originally featured on The Conversation.

The dinosaurs were killed by a meteorite impact on the Earth some 66 million years ago in what has become known as the Cretaceous-Paleogene extinction event. At what time of the year this occurred has long generated debate among palaeontology enthusiasts.

A recent study published in Nature builds on earlier evidence to suggest the dinosaurs probably met their demise in June. The fact that researchers have been able to pinpoint the timing of an event that happened millions of years ago is a remarkable feat of science—but more on that later.

The latest evidence comes from a site called Tanis, located in the Hell Creek Formation in North Dakota. Tanis is one of several geological locations around the world where scientists have observed the Cretaceous-Paleogene boundary in the succession of sediments.

Tanis has yielded wonderful fossils of dinosaurs, early mammals, fish, plants and other things. Many of these fossils are exceptionally well preserved, with some showing remains of soft tissues, such as skin, as well as bones, which can offer valuable scientific insights.

The Tanis site was first identified in 2008 and has been the focus of fieldwork by palaeontologist Robert DePalma since then. In a 2019 paper, DePalma and his colleagues argued that Tanis captured the moment of the asteroid’s impact, due to three factors.

The first was the presence of dinosaur fossils occurring in the Cretaceous sediments right up to the Cretaceous-Paleogene boundary, and exactly at the boundary at the time of impact.

The second was a layer of melt spherules: tiny glass balls that cooled in flight from molten rock. When the asteroid struck Earth in the region of what is now the Yucatán Peninsula in Mexico, it spread debris and melt spherules for thousands of kilometers.

The third was evidence of seiche waves (see-saw-like standing waves) in deep channels. The Tanis site is well inland today, but at the end of the Cretaceous period it was located on the coast of the western interior seaway that divided North America at that time, with sea levels some 200 metres higher than they are today. The site was estuarine, which means fresh and salt waters were mingling.

The seiche waves were generated by the distant impact in Mexico, which set off seismic waves that shook the Earth and caused water to flow in and out of the river channels at a fast rate, estimated as beginning one hour after the impact.

As well as melt spherules within the fossil-bearing rocks, the researchers found abundant spherules in the gill skeletons of some of the fish they examined. We can imagine that as they floundered in the violently oscillating waters of the river channel, they could have swallowed melt spherules coming from above.

Looking more closely at the fish

In December 2021, DePalma and his colleagues published an important paper about the timing of the Cretaceous-Paleogene extinction event. In this study, they analysed some of the exceptionally well-preserved fish bones, looking at how the cycle of seasons, from summer to winter, were documented in the structure and chemistry of the bones.

By comparing living sturgeon to sturgeon fossils from Tanis, they found that in a fin spine, regular layering at a scale of millimeters shows the fish died when it was seven years old. The growth rings confirm the fish alternated between fresh waters in summer months and saline waters in winter. In this and other specimens analyzed in the same study, the last growth increment matches the transition from spring to summer.

Taken together, this suggests the meteorite struck in May or June, being the cusp of spring and summer in the northern hemisphere.

Importantly, these findings confirm earlier evidence based on fossil plants, which suggested the extinction event took place in early June.

Palaeobotanist Jack Wolfe identified a location in Wyoming that showed the effect of the meteorite on a freshwater lake. At the point of impact, the lake froze, preserving fossil plants in exquisite detail.

By comparing the fossil plants to similar modern water lilies Nuphar and Nelumbo, he showed that the latest Cretaceous water lilies in the lake had been halted in their growth at a point in their trajectory of producing summer leaves, flowers, and fruit which indicated freezing in early June.

Palaeontologists often say they would need a time machine to understand the details of past life, such as the month the dinosaurs died out. But here we see extraordinary conclusions can emerge from careful analysis and rational comparison with the modern day.

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Location is everything, for both homeowners and dinosaurs. When you’re buying a house, it’s better for your long term happiness to find a neighborhood you like that’s close to work instead of having that extra living room. And when you’re a Cretaceous period dinosaur, it’s better for your long term survival to have a giant asteroid hit in the middle of the ocean instead of just off the coast of Mexico.

So, assuming that in fact there was one big impact that killed off most dinosaurs, the meteor responsible hit near the Yucatan Peninsula, where it was free to kick up dust from vaporized rock and sulfur dioxide. Sure, plenty of feathered dinosaurs died from the explosive force of the asteroid hurtling towards them—it was equivalent to about ten billion Hiroshima-sized nuclear bombs—but lots of them died later, too.

Our very-distant ancestors were right there alongside ancient crocodiles and sharks and gosh darn it, they prevailed. We have since made it out of the food chain, with the exception of those people who try to befriend those godless killing machines: bears. And apparently, none of it would have been possible if that meteor had shown up 30 seconds later. The early bird catches the worm—but it still sucks for the worm.

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Scientists have identified an extremely rare fossilized dinosaur embryo in an egg from southern China.

The late-Cretaceous specimen belongs to a group of dinosaurs called oviraptorosaurs, which are closely related to birds. Intriguingly, the embryo’s position resembles the “tucking” posture that modern birds assume before hatching. The findings indicate that this important adaptation evolved before birds split off from other dinosaurs, the researchers reported on December 21 in the journal iScience.

“Dinosaur embryos are key to the understanding of prehatching development and growth of dinosaurs,” Fion Waisum Ma, a PhD student in paleobiology at the University of Birmingham in the United Kingdom and coauthor of the findings, said in an email. While fossilized dinosaur eggs are abundant, however, embryos are much harder to come by. The dinosaur embryos that paleontologists have found are usually incomplete, with bones that have separated and become jumbled. 

By contrast, the newly described fossil includes an almost complete skeleton with bones arranged much as they were in life. “This little dinosaur is beautifully preserved in a fossilized egg,” Ma said. “We suspect the egg was buried by sand or mud quickly enough that it was not destroyed by processes like scavenging and erosion.”

She and her colleagues were able to reveal more than half the skeleton, with the rest still covered by rocky material in the egg. The fossil, originally discovered in an industrial park in China’s Jiangxi Province, dates to roughly 71 million to 65 million years ago. The elongated egg is 16.7 centimeters (6.6 inches) long and 7.6 centimeters (3 inches) wide, while the skeleton curled inside has a total length of 23.5 centimeters (9.3 inches).

[Related: A newfound South American dinosaur had a tail like a war club]

Oviraptorosaurs have been found in present-day North America and Asia. This dinosaur family is known for its diverse variety of skull shapes, including some with very tall crests. Had the embryo hatched, it probably would have grown into a medium-sized oviraptorosaur, Ma said, perhaps reaching 2 to 3 meters (6.6 to 9.8 feet) in length. The dinosaur would have been covered in feathers and had a toothless skull. 

The researchers compared the embryo’s anatomy with that of other oviraptorosaurs and theropods, the broader category of carnivorous dinosaurs that also includes Tyrannosaurus rex. The researchers also examined a fine slice of eggshell under the microscope and analyzed the evolutionary relationships among oviraptorosaurs to determine where the new embryo fell on the family tree. They concluded that the embryo belonged to a subgroup of oviraptorosaurs called Oviraptoridae. 

“The most surprising observation is the posture of this specimen—its body is curled with the back facing the blunt end of the egg, [and] the head below the body with the feet on each side,” Ma said. “This posture has never been recognized in a dinosaur embryo, but it is similar to a close-to-hatching modern bird embryo.”

To prepare for hatching, bird embryos reposition themselves in a process known as tucking. The oviraptorid fossil Ma and her team examined is arranged much like a 17-day-old chicken embryo in the first, or pre-tucking, phase. Over the next three days, a chicken embryo would gradually move into the final tucking posture, in which the body is curled with the head under the right wing. This posture seems to stabilize and direct the head while the bird cracks the eggshell with its beak, Ma said.    

She and her colleagues suspect that several previously discovered oviraptorid embryos are also arranged in various phases of tucking, although it’s hard to be certain because those specimens aren’t as well-preserved. Still, the team concluded that oviraptorids and modern birds may have used a similar strategy to maximize their chances of hatching successfully, unlike their more distant cousins such as the long-necked sauropods and living crocodilians.

[Related: Whoa, dinosaur eggs looked more dope than we thought]

“Tucking behaviour was usually considered unique to birds, but our new findings suggest that this behaviour could have existed and first evolved among theropod dinosaurs—the ancestors of modern birds,” Ma said.

To confirm this possibility, however, researchers will have to unearth more fossilized embryos of theropods and other kinds of dinosaurs to compare with modern birds and crocodiles. Ma and her colleagues also plan to investigate the skull and other body parts of this embryo still hidden within the rock.

“We hope to answer more questions about dinosaur early development and growth with this exceptional specimen,” she said.

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A new species of armored dinosaur from subantarctic Chile boasted a large tail weapon that looked dramatically different from those found on its relatives, and may shed light on a mysterious phase in the group’s evolution. 

Scientists found the mostly-complete skeleton in 2018 in the Río de las Chinas Valley of Chilean Patagonia and determined it to be roughly 71.7 to 74.9 million years old, dating it to the late Cretaceous. When they further examined the skeleton, the researchers found a baffling mixture of features typically seen in ankylosaurs and stegosaurs. However, its “bizarre” tail didn’t seem to match with the tails seen in either of these famous groups; rather than the traditional spikes or clubs, the newly-named Stegouros elengassen had seven pairs of bony deposits encasing half the tail in a flattened frond-like structure, the researchers reported on December 1 in Nature. 

Still, an analysis of the armored dinosaur family tree revealed that the fossil belonged to an ankylosaur, suggesting that different branches of the group flourished in the northern and southern hemispheres after the supercontinent Pangaea broke up. 

“This is the first time scientists get a good look at what a South American ankylosaur is like,” says Alexander Vargas, a paleontologist at the University of Chile in Santiago and coauthor of the study. Stegouros’s tail weapon, he adds, is “absolutely unlike anything we have seen before.”

A number of present-day mammals and reptiles, including porcupines and alligators, use their tails as whips or lashes to defend themselves from predators or rivals. But southern African girdled lizards go a step farther: Their tails are equipped with bony spines. More elaborate versions of these tail armaments were once wielded by extinct relatives of turtles and armadillos. 

“But the champions of them all are the armored dinosaurs,” Vargas says. In addition to the bony plates and spines along their backs, some members of this group developed specialized tail weapons. These included the tail spikes seen in stegosaurs such as Stegosaurus and rounded tail clubs belonging to ankylosaurs such as Ankylosaurus.

The ankylosaurs generally had broad backs and thick limbs. While ankylosaur fossils are plentiful in North America and Asia, Vargas says, until now only fragmented bones and teeth have been found of their more southern cousins. 

“These scraps and pieces were often interpreted as a sign that ankylosaurs, which in North America were very abundant and diverse, somehow managed to cross into South America, to migrate,” he says.

The specimen that he and his colleagues discovered in 2018 at the southern tip of South America changes this picture, Vargas says. When the team began to excavate the fossil, they first noticed its slender limbs and speculated that the specimen might have been a bipedal herbivore. Next came the tail with its “astonishing weapon,” Vargas says, which indicated that the skeleton actually represented some kind of armored dinosaur. 

“We thought we might have a stegosaur when we uncovered the hips,” he says. “They were identical to a stegosaur.” The fossil’s upper arm and right hand also resembled those of stegosaurs. Yet when the team reached the skull, they found that the upper jaw and palate looked distinctly ankylosaurian.

[Related: An overlooked fossil turned out to be a new herbivorous dinosaur with an oddly shaped nose]

To find out which group the puzzling species belonged to, the researchers analyzed hundreds of different traits from dozens of dinosaur species and ultimately identified ​​Stegouros as an ankylosaur. What’s more, its ancestors split off from the rest of the ankylosaurs some 167 million years ago in the mid-Jurassic. 

“It’s an evolutionary link between the ankylosaurs…and other armored dinosaurs like the stegosaurs,” Vargas says. 

This could explain why Stegouros bears so little resemblance to most ankylosaurs, with its agile limbs, narrow feet, light armor, and a hawk-like beak. The petite ankylosaur was only about 2 meters (6.6 feet) long and had a shorter tail than other armored dinosaurs. The weapon’s flattened shape might have made it easier for Stegouros to avoid dragging its tail and “being able to wield it for defense,” Vargas says. He and his colleagues named the structure after an Aztec war club, or macuahuitl, which resembles a wooden sword with obsidian blades protruding from either side.  

The researchers determined that Stegouros is closely related to two other ankylosaurs from Australia and Antarctica. The latter, which is known as Antarctopelta, features “enigmatic” bony plates that have perplexed scientists but which might be part of the same kind of macuahuitl used by Stegouros, Vargas says.  

The findings suggest that Stegouros “is not an invader from the north,” he says. “It is actually a lineage that has roots so deep in time it’s [from] when all continents were together.”

As Pangaea finished separating into Laurasia (present-day North America and Eurasia) and Gondwana (which would become South America and the remaining continents) in the late Jurassic, the more familiar ankylosaurs would come to dominate the northern continent while Stegouros and its relatives laid claim to the south. 

For their analysis, Vargas and his team only described a single Stegouros specimen. They plan to search for more complete skulls in the future that can be compared with those of the ankylosaurs from Antarctica and Australia. The findings also emphasize how little is still known about the evolutionary history of armored dinosaurs in the southern hemisphere, the researchers concluded.

“You can expect more surprises from the south,” Vargas says.

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In the 1960s, Australian coal miners stumbled across huge, bird-life footprints protruding from the ceiling of their subterranean work site in south-eastern Queensland. The marks, more than a foot long, belonged to a creature that trekked across swampy land around 250 million years ago. They sent paleontologists into a tizzy, who though the tracks belonged to a carnivorous dinosaur—a creature larger than any other predator of its time.

Some fossil experts across the globe had their doubts about the footprints coming from a predator, though. But they couldn’t quite disprove the carnivore idea because all they had access to was black and white photos and a drawing of the tracks. With 3D modeling technology today, researchers have been able to analyze the impressions further, and identify the mysterious creature as an herbivore from the group Prosauropoda.

[Related: Dinosaurs who stuck together, survived together]

“We can now make 3D models, 3D visualizations, and augmented reality so that we can get not only a clearer and more detailed understanding of the fossil that we’re examining, but also communicate that in a more complete manner,” says Anthony Romilio, paleontologist at University of Queensland and lead author on the new study published in Historical Biology. He and his team used casts of one of the prints, made by geologists and the Queensland Museum back in 1964, to create a 3D model of the dinosaur’s foot to better understand it’s entire body.

Once the track was digitized, the researchers took exact measurements from the cast and verified them with the 3D model. Back in the ‘60s, scientists had to pull estimates from the single drawing and photos; their estimates put the the print as several centimeters longer than its actual length. Without certainty of the size of the print, it’s difficult to gauge the true nature of a long-extinct dinosaur.

Using the updated dimensions, and his colleagues multiplied the length of the dinosaur’s foot by a factor of four, which gave them the rough length of the leg up the hip joint. Smaller feet mean smaller legs, helping to create a picture of the entire dinosaur that indicated it was not a predator.

Even before he knew the proper size of the creature’s feet, however, Romilio had doubts about its supposed predatory behavior. Had it been a carnivore, it would have been the biggest predator of the Triassic period—which explains all the hubbub around the discovery decades ago. But other fossil finds show that dinosaurs of the previously estimated size didn’t turn up until millions of years later during the Jurassic period.

By distilling a 3D model of the track, Romilio and his team were able to make the original discovery more accessible to paleontologists across the world. Romilio also created an augmented reality visual of the dinosaur and its footprints, so that everyone, not just researchers, could see this creature on their iPhones and iPads. 

“This allowed a more comprehensive discussion about these footprints,” says Hendrick Klein, an expert on Triassic dinosaurs at the Saurierwelt Paläontologisches Museum in Germany. Romilio reached out to him for a second opinion after the study team realized the exact measurement of the foot came from a dinosaur that was smaller than imagined. Once Klein was involved, he corroborated the idea by looking at the Australian tracks against that of other Triassic herbivores.

“I remember that I had excavated footprints in North America, and had also seen similar footprints in Italy,” Klein says. “I compared Anthony’s results with these footprints, and what I distinctly saw was that they share similar morphology.” 

One particular feature Klein noted was the rotation of the print. The track is directed strongly towards the midline of this creature’s foot, indicating that the dinosaur’s steps rotate inwards, a feature that isn’t typically seen among predatory dinosaurs. 

Klein and Anthony both stress that prehistoric footprints are vital to understanding the fossil record. No one has identified skeletal dinosaur remains from the Triassic period in Australia yet, so researchers only have these small indications of life to better understand the continent’s past. They just have to get the math right; 3D tech will help.

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During the early Jurassic Period, some 200 million years ago, the only large herbivores in many ecosystems were long-necked dinosaurs called sauropodomorphs. These reptiles were the forerunners of the gargantuan sauropods, the group that included Brachiosaurus and Brontosaurus.

A well-populated breeding ground in southern Patagonia hints at one reason early sauropodomorphs were so successful: They knew how to stick together. When scientists analyzed the eggs and skeletal remains of juveniles and adults of a species known as Mussaurus patagonicus, they found that the fossils were segregated by age, suggesting that the dinosaurs raised their young as a community. 

The 193-million-year-old site represents the earliest evidence of herd-living in dinosaurs, the team reported on October 21 in Scientific Reports.

“People have known for a long time that the more advanced dinosaurs, the ones that lived in the late Jurassic and Cretaceous, especially the large sauropods…moved and lived in herds,” says Jahandar Ramezani, a geochronologist at MIT and coauthor of the findings. “But the question has always been, when did this behavior start?”

The species that he and his colleagues investigated was originally discovered in Argentina’s Laguna Colorada Formation in the 1970’s. In recent years, the team has excavated dozens more Mussaurus specimens of all ages from the site. The youngsters appear to have walked on four legs before becoming bipedal as they matured. The largest adult specimen would have reached an estimated 1504.8 kilograms (about 1.7 tons) in size.

In total, the researchers examined more than 100 eggs and 80 Mussaurus skeletons from an area of about 1 square kilometer (about 0.39 square miles). The team used x-ray imaging to peer inside the eggs and confirm the embryos’ identities. To determine the juvenile dinosaurs’ ages, the researchers counted the annual growth rings visible in fine slices of leg bone under the microscope.

The fossils were found close together, in three levels within an area of reddish-brown siltstone that appears to have been a shared breeding ground, Ramezani says. He and his colleagues observed that many of the fossils were grouped by age, including several nests with clusters of eight to 30 eggs, a collection of 11 juveniles that were the same size and appeared to have died and been buried together, and adults alone or in pairs.

[Related: This Australian behemoth is officially the largest dinosaur on the continent]

“This age segregation is basically key; it tells us that this is not something like a simple family structure, being parents and juveniles together,” Ramezani says. “These are colonies of a lot of dinosaurs that are basically taking care of the young [and] the eggs together.”

The sediments found amongst the fossils indicate that the site was located near a short-lived lake, he says. The researchers speculate that the dinosaurs might have died after a long drought, then been rapidly buried in windblown dust.

Mixed in with this dust there was also some volcanic ash, which contains minute zircon crystals. These crystals have high levels of uranium that over time decays into lead. By analyzing the amounts of both elements in the crystals, Ramezani and his team were able to calculate the age of the sediments the dinosaurs were buried in. They found that the site was 193 million years old, pushing back the earliest recorded herding behavior in dinosaurs by at least 40 million years. 

However, it’s likely that dinosaurs began gathering in herds to forage and care for young together even before Mussaurus appeared on the scene. This strategy may have enabled sauropodomorphs and possibly other early dinosaurs to thrive and eventually dominate ancient ecosystems, Ramezani says. 

In fact, paleontologists have reported nesting colonies of other early sauropodomorphs from China and South Africa that appear to have lived around the same time. 

“They have some ideas based on the rocks what the approximate ages would be, but they don’t have the exact ages,” Ramezani says. “We definitely need more information, better [estimates of] ages, to be able to put these pieces of the puzzle together and complete the picture of this social behavior.” 

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When it comes to snakes, the modern world offers an embarrassment of riches. There are almost 4,000 different snake species alive today, placing the group not far behind mammals in terms of diversity. The snakes are also varied in the types of food they prefer to consume: Some feast only on earthworms, while others can swallow an entire deer. 

“T​​hey just have an astounding variety of diets,” says Michael Grundler, a postdoctoral researcher in ecology and evolutionary biology at the University of California, Los Angeles. He and his colleague Daniel Rabosky, of the University of Michigan, wanted to know how this group became so diverse and successful. 

When they analyzed both the diets and the evolutionary relationships amongst hundreds of present-day snakes, the pair found that the mass extinction that finished off the dinosaurs was a game-changer for the limbless reptiles. Early snakes slithered into newly vacant ecological niches and rapidly evolved the ability to go after a wide array of prey, the scientists reported on October 14 in the journal PLOS Biology.

Little is known about the earliest chapters of snake evolution because the animals are rarely preserved as fossils, Grundler says. So he and Rabosky used information from living species to probe their history. They gathered more than 34,000 reports of the diets of 882 species based on observations of wild snakes and dissected museum specimens. The researchers also drew upon family trees determined from the genetics of modern snakes.

“With those two pieces of information we can make inferences about what extinct species might have looked like long ago,” Grundler says. The team used mathematical models to reconstruct how quickly these ancestral snakes might have changed through time as their diets shifted.

The earliest snakes were probably insect-eaters. However, by the time the dinosaur-killing asteroid arrived 66 million years ago, they’d branched out a bit to dine on vertebrate prey.

“Shortly after that event we find a signal of a big explosion in dietary diversity,” Grundler says. “The survivors of that event went on to evolve this huge range of eating styles that we see today.”

After this burst of activity, many groups also changed their diets very quickly when they journeyed to new locations. One particularly striking example is the dipsadine snakes, a subfamily with more than 700 species that include hognose snakes and false coral snakes. After arriving in South America, “They just exploded in their dietary diversity in a relatively short period of time,” Grundler says. “They evolved to specialize on earthworms, fishes, frogs, slugs, eels—even other snakes.”

[Related: These snakes wiggle up smooth poles by turning their bodies into ‘lassoes’]

On the other hand, some groups of snakes evolved far more slowly. Blind snakes, which feed mainly on colonial insects like ants and termites, appear to have had similar diets for tens of millions of years, Grundler says. 

The findings highlight how opportunities such as the disappearance of hungry competitors (and the rise of rodents and other delicacies) and moving into new habitats “shape evolutionary fortunes,” he adds.

For snakes, this led to a spectacular collection of adaptations for dining on mammals, birds, fish, amphibians, other reptiles, and a host of invertebrates. The emergence of venom allowed vipers and other ambitious snakes to bring down prey that might otherwise be too dangerous for them to subdue. 

There were also more unusual developments; members of the Pareinae subfamily in southeast Asia that dine exclusively on snails have more teeth on one side of their jaw than the other. This makes it easier for the snakes to “get in and rake the body of the snail” to extract the hapless animal from its asymmetrical shell, Grundler says.

At the same time, he and Rabosky observed, even snakes that are apparently specialized for one kind of prey have been known to gobble up other animals that come their way. This capacity for adventurous eating may have helped early snakes innovate and thrive throughout their history. 

While the new analysis covers all the major snake families, Grundler says, it only includes around a quarter of known species. “There’s thousands of species of snakes for which we know very little,” he says. “We still have a long way to go.” 

The next step will be to gather more information about these mysterious snakes and search for more information from the remains of their extinct relatives.

“This [work] all relies on living species,” Grundler says. “If we’re able to get better observations of diets of fossil snakes and include those in our analysis, that would be really important to do.”

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What do you think something called a hell heron might look like? Herons living today are necky, leggy birds with needle-sharp beaks. You might imagine an infernal version of this creature could also have horns or breathe fire. But in truth, it was a dinosaur with crocodile teeth. At least that’s what scientists have determined after a recent discovery of fossilized remains on the British Isle of Wight.

The hell heron is actually one of two new dinosaur species found, both from the family Spinosauridae, making these creatures spinosaurids, or spined dinosaurs. The new findings were published Wednesday in the journal Scientific Reports.

“Spinosaurs are cool,” says Neil Gostling, an evolutionary biologist at the University of Southampton who oversaw the fossil analysis. “I don’t normally use terms like ‘cool’ because I’m not cool enough to use terms like ‘cool.’” If a person who typically avoids using “cool” describes a dinosaur that way, this dinosaur must be pretty rad.

One thing that makes them so wicked awesome is that these specific Baryonyx were Frankenstein-esque terrestrial theropods, with nearly 30-foot-long bodies similar to a T. rex, but 3-foot-long heads more like crocodiles. Their narrow snouts and sharp, curved teeth could’ve been a dead ringer for the domes of the more familiar Australian terrors, though the two species are not directly related. 

[Related: What would a dinosaur taste like?]

While these spinosaurs lived on land, they were unusual in that they were probably aquatic hunters who skulked for fish in rivers. That’s where the “heron” part comes from: Scientists believe they would strike for fish much in the way that modern herons hunt. 

The hell heron has been specified as Ceratosuchops inferodios, which translates to “horned crocodile-faced hell heron.” The other is called Riparovenator milnerae, which means “Milner’s riverbank hunter,” in honor of the late British paleontologist Angela Milner.

Neither Gostling nor his team found the fossils; instead, they were discovered and donated by two fossil collectors, Brian Foster and Jeremy Lockwood, who donated their loot to the Dinosaur Isle museum. According to Gostling, the Isle of Wight is the best place in Europe to find dinosaur fossils, and one of the top ten places in the world, partially because the isle is eroding. 

As for the new fossils themselves, Gostling and his team were working with two early Cretaceous-era finds from about 125 million years ago. One is a part of the snout at the front of the face, and the other is part of the skull case. They’ve got 50 other parts of the jaw to work with, so they’ve been able to recreate approximately what one of these two dinosaurs looked like.

Gostling says that while these dinosaurs are similar, he’s uncertain they lived at the same time;  they could have been separated by a million years, in fact.

While these finds might not overturn any one aspect of paleobiology, Gostling says that at the very least more experts have their eye on spinosaurids because of them. This fossil analysis also yields a migratory map.

“We can see from our analysis is that spinosaurs originate in Europe, and then migrate into South America, into Asia and, into Africa,” says Gostling. “That’s the really exciting thing we’ve got, the answers to geography questions as well as trying to address the ecology in terms of the diversity of animals. “

Correction 10/5/2021: This article previously misidentified the hell heron as being from the genus Baryonyx. It is a Baryonchine spinosaur, but not of that genus.

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Movies like Jurassic Park may give the impression that we know everything about dinosaurs, including how they used to walk or run. But it’s actually incredibly difficult to figure out how extinct creatures moved their bodies. 

Now, a fruitful combination of computational biomechanics and so-called “predictive simulation” are helping fill in these locomotive knowledge gaps.  

To replicate the movements of a Triassic dino that lived around 200 million years ago, Coelophysis bauri, a team of researchers with diverse expertise developed a novel 3D simulation program. According to their results, small, two-legged dinosaurs like C. bauri likely swung their tails as they walked or ran—similar to how humans swing their arms. They reproduced how different muscles would interact, and looked at how C. bauri’s gait and momentum would have been impacted by tail movements. 

The tail, it turned out, regulated angular momentum and efficiency, reducing the muscular strain on the dinosaur’s body. The team believes this mechanism likely applied to other dinosaurs as well. The research was published in Science Advances.

Previously, paleontologists mostly believed that the tail was just a passive counterbalance that offset the weight of dinosaurs’ heads and necks, evolutionary biomechanist and co-author Peter Bishop told Live Science. “We didn’t really have expectations or hypotheses leading into this,” he added. “We assumed that [the tail] would just be there hanging.”

[Related: What would a dinosaur taste like?]

To make sure their model was consistent with real-life biomechanics, the team first used it to simulate birds called tinamous, elegant Central and South American avians with anatomy similar to bipedal dinosaurs. When they were sure that their simulation could faithfully replicate the bird’s bodily movements in real life, they turned their model to the C. bauri dinosaur. 

To really get at the tail’s importance, the team repeated the simulation, but removed the dino’s tail from the model. The simulated C. bauri had to move its pelvis differently. “When we chopped the tail off, the dinosaur was effectively having to wag its hips to compensate for the loss of the tail,” Bishop told The Guardian.

The tailless dino also had to increase its muscle effort by 18 percent, which suggests that the tail also helped keep energy expenditure low. When the team repeated the model and forced the tail out of sync, C. bauri again had to really up its energy use to travel at the same speed. 

“It’s always good to see robust computational biomechanics approaches applied to dinosaur locomotion,” said Nizar Ibrahim, a vertebrate paleontologist at the University of Portsmouth who is unaffiliated with the recent research, to Gizmodo. Ibrahim was the lead author of a study published in Nature last year that showed how one giant dinosaur, Spinosaurus aegyptiacus, may have used its tail to help it swim. He added that new work like this 3D simulation is adding to a growing body of research supporting the idea that “dinosaur tails were more dynamic and complex than previously assumed.”

Now that they have this simulation at the ready, Bishop hopes to apply it to all kinds of creatures of yore. “We are now primed to explore locomotion and other behaviors in a whole host of other extinct critters, and not just dinosaurs,” Bishop told Gizmodo. “Pretty much anything is fair game.”

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Unless someone finds well-preserved dinosaur DNA and decides to breed, say, free-range Velociraptors in an agricultural twist on the standard Jurassic Park scenario, we’re probably not ever going to taste the flesh of the roughly 700 species of extinct dinos. But we can hypothesize, and the answer is a lot more complicated than “dinosaurs probably tasted like chicken.”

Let’s get one thing out of the way first: If you’ve eaten any type of bird, you’ve eaten dinosaur. Modern birds are the last living therapods—the same group of animals that includes Tyrannosaurus rex and Velociraptor—so they’re not simply “descended from” dinosaurs, they are dinosaurs.

So yes, chicken (a dinosaur) tastes like chicken. Crocodilians (like alligators), which share a common ancestor with dinosaurs, also kind of taste like chicken. And that’s a good starting point when you’re thinking about what Stegosaurus or Compsagnathus might’ve tasted like.

“In evolutionary biology terms, there is an extant phylogenetic bracket of chicken-tasting animals—crocs and birds—surrounding the dinosaurs on the family tree, making it reasonable that the dinosaurs had a chicken taste too,” says Steve Brusatte, a paleontologist and professor at the University of Edinburgh.

But it’s not that simple. Every bird has a unique taste. If you’ve eaten duck in the US, it was probably the American Pekin, a domesticated mallard with a mild, somewhat gamey taste. Merganser, another type of duck, is quite fishy and some people find it unpalatable. Extinct dinosaurs likely had similarly varied flavor profiles.

There are also countless factors that go into making something taste the way it does, but two of the most important are muscle usage and diet.

Triceratops and Allosaurus likely had fast- and slow-twitch muscles like people and other animals do. Slow-twitch fibers are associated with dark meat—thanks to reddish hues linked to the oxygen-carrying protein myoglobin—while fast-twitch fibers are associated with white meat.

Smaller predatory dinosaurs probably had to move quickly to ambush prey and dart away from threats, so they might’ve had a fair amount of white meat. Velociraptor may have truly tasted like chicken. Larger dinos, on the other hand, likely had large muscles that were constantly moving and needed a lot of oxygen, so they might’ve more closely resembled beef or venison.

Animals can also take on the flavor of things they eat. Grass-fed beef can be a bit more earthy than corn-fed cattle, for example. Dinosaurs, however, probably didn’t eat much grass, as it didn’t evolve until the very end of their 165 million-year reign. Therapods had a varied diet, while herbivores chowed down on ferns, cycads, and conifers, to name some ancient plants that are still around today.

Today, deer eat a similar diet, so some dinosaurs could’ve tasted like venison. They also may have been gag-inducing—the spruce grouse, a chicken-like bird, spends its winters munching almost exclusively on conifer needles. If you eat one at that time, it can taste heavily of spruce, almost like turpentine, says Hank Shaw, a chef and outdoorsman who specializes in wild foods.

Ultimately, there’s no definitive answer for what extinct dinosaurs might’ve tasted like, but we can let our imaginations run wild. And if someone ever does acquire the ability to bring dinosaurs back from extinction, we’d do well to remember that the Jurassic Park movies don’t end with people eating their creations—more often, it’s the other way around.

Is your head constantly spinning with outlandish, mind-burning questions? If you’ve ever wondered what the universe is made of, what would happen if you fell into a black hole, or even why not everyone can touch their toes, then you should be sure to listen and subscribe to Ask Us Anything, a brand new podcast from the editors of Popular Science. Ask Us Anything hits Apple, Anchor, Spotify, and everywhere else you listen to podcasts every Tuesday and Thursday. Each episode takes a deep dive into a single query we know you’ll want to stick around for.

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Rising out from the Kyzylkum Desert of Uzbekistan is the Bissekty Formation, a structure of rock and sediment between 90 and 92 million years old that has preserved many a dinosaur fossil. Out of this formation, paleontologists have discovered an imposing new dinosaur species that was likely the apex predator of the area at the time.

The discovery, Ulughbegsaurus uzbekistanensis, was a carcharodontosaur, or a “shark-toothed” dinosaur, a kind of allosaur characterized by its large size and serrated teeth. It’s the first of its kind to be found in Central Asia. And while paleontologists only had a single fossil to work with—a part of the dino’s upper jaw—researchers have concluded that this specimen likely measured around 26 feet (8 meters) in length and weighed about 2,200 pounds (1,000 kilograms). 

Those massive dimensions means that U. uzbekistanensis was twice the length and more than five times heavier than the predator previously thought to be the apex of the area, the tyrannosaur Timurlengia, which measured 13 feet (4 meters) in length and weighed in at 375 pounds (170 kilograms). The findings were published in Royal Society Open Science.

[Related: The real Jurassic Park may have been in the Arctic]

“The skull would have measured about a meter. It had knife-like, sharp teeth and was a meat-eater,” lead researcher of the study, paleontologist Kohei Tanaka, told Express. 

University of Minnesota paleontologist Peter Makovicky, who was not involved in the study, agreed with the paper that U. uzbekistanensis was likely at the top of the local food chain. “I think this bone is so big that this would have been a very large predatory dinosaur and very likely the apex predator in its ecosystem,” he told Live Science. 

The giant jawbone was found in Uzbekistan in the 1980s, but researchers rediscovered the fossil when looking through the collection of an Uzbekistan museum. Senior author and Hokkaido University Museum paleontologist Yoshitsugu Kobayashi explained in a statement the value of this finding: “The discovery of Ulughbegsaurus uzbekistanensis fills an important gap in the fossil record, revealing that carcharodontosaurians were widespread across the continent from Europe to East Asia.” 

The study authors also write that, sometime before the Late Cretaceous period (between 66 and 100 million years ago), carcharodontosaurians like Ulughbegsaurus disappeared from Central Asia, ceding that top predator spot to tyrannosaurs. But a scarcity in research and fossil discovery means that not a lot is known about this transition. U. uzbekistanensis is now the latest known carcharodontosaur known to coexist with tyrannosaurs in this time period. 

“For many tens of millions of years, tyrannosaurs were the understudies of the allosauroids,” University of Edinburgh paleontologist Stephen Brusatte, who was not involved in the new research, told Smithsonian Magazine. “Allosauroid” refers to the larger family that carcharodontosaurians like Ulughbegsaurus belonged to.

Though it’s clear that tyrannosaurs took over the area as carcharodontosaurs disappeared, it’s still unclear why, and new fossils like this can help illuminate the question: “Given that allosauroids were holding back tyrannosaurs for so many tens of millions of years, I can’t envision that tyrannosaurs suddenly figured out how to out-compete [them],” Brusatte said. Having this new fossil, therefore, is a great new piece of the puzzle to have: “This is one new bone, and really just part of a bone, but its importance far eclipses its looks.”

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In the central Chinese province of Henan, a farmer discovered a black orb with a vaguely blue tint, about the size of a billiards ball. While he and initial researchers thought they had found a dinosaur egg, it turned out to be something much rarer: a huge fossilized turtle egg—with an intact turtle embryo still inside. 

The biggest turtle eggs today are just a few inches long, with papery thin shells. The newfound fossil is massive by comparison. Paleontologists concluded that the egg belongs to the nanhsiungchelyids, an extinct group of land-dwelling turtles that lived alongside dinosaurs 145 to 66 million years ago, during the Cretaceous period. The turtle parent who laid the hefty egg was likely quite the beast—researchers estimate that its shell was more than 5 feet and 4 inches long. The new paper was published today in the Proceedings of the Royal Society B. 

“This is actually the first time that [fossil] turtle eggs or a nest really could be attributed to a particular turtle,” Darla Zelenitsky, a co-author of the study and a paleontologist at the University of Calgary, told CBC. She added that the egg could have been entombed when a nearby river system overflowed during the rainy season, thus preserving it as a fossil. 

[Related: We may finally know where young turtles spend their ‘lost years’]

The physiology of the ancient embryo is surprisingly similar to those of modern turtles. Raul Diaz, a reptile evolutionary biologist specializing in embryos at California State University at Los Angeles who was not part of the study, told National Geographic that the specimen’s bone structure is more or less what you’d expect to see today. “It’s almost—in my head—indistinguishable from what I would see in the lab.”

While the fact that turtles and dinosaurs once roamed side by side is well-established, the rarity of fossilized eggs (let alone with intact embryos) means that very little is known about the animals’ nesting practices. This egg, and its robustness, give paleontologists more clues.

The nanhsiungchelyid turtle shell is four times thicker than those of the biggest Galapagos tortoises today. That thickness may have been an adaptation to keep embryos safe in a hot and dry climate, or as a way to prevent breakage when the eggs were buried under mounds of wet soil. 

It also bolsters the theory that these turtles spent all their time on land, Jordan Mallon, a paleontologist at the Canadian Museum of Nature in Ottawa not involved in the research, told CBC. He added that this has been debated for some time, and that the techniques in the study could later be used to answer lingering questions about the evolution of turtles, for example how their shell characteristics have changed over the millennia.

These turtles’ land-based lifestyle may have also been their undoing. The nanhsiungchelyids were wiped out approximately 66 million years ago by the same fated asteroid that killed the dinosaurs. Other more aquatically-inclined turtles survived the blast, perhaps shielded by their underwater dwellings. Whether that’s the whole story remains to be seen, but after the Cretaceous period, nanhsiungchelyid turtle shells disappeared from the fossil record, never to be seen again.

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Paleontologists have discovered three new early mammal species that dwelled in present-day Wyoming shortly after the dinosaurs went extinct, suggesting that this early chapter in the dawn of mammals was more diverse than previously recognized. 

The researchers examined the fossilized teeth and jaws of the mammals, which were about the size of a giant rodent or small cat. They found that they belonged to a group called condylarths, or archaic ungulates, which includes the ancestors of today’s hooved animals. These specimens lived within the first 328,000 or so years after the dinosaurs disappeared, a time known as the early Puercan age.

Most sites in the western United States and Canada with fossils from this period contain largely the same few mammal species, says Jaelyn Eberle, a curator at the University of Colorado Museum of Natural History in Boulder. She and her colleague Madelaine Atteberry reported the new findings on August 18 in the Journal of Systematic Palaeontology. 

“Here we have one [site] where there’s a bunch of new guys on the scene,” Eberle says. “The diversification of mammals occurred, or certainly started, sooner than what we would predict from looking at other areas.”

After a massive asteroid struck Mexico’s Yucatán Peninsula about 66 million years ago, many mammals went extinct along with the dinosaurs. Those that remained would generally have been the size of mice or rats. The most abundant group of mammals in North America during this time was the condylarths. Their fossilized teeth don’t appear to be specialized for dining on flesh or plants, and they may have been omnivores.

The condylarth teeth that Eberle and Atteberry examined had previously been collected from a sandstone river channel in a quarry in south-central Wyoming’s Great Divide Basin. Teeth are hard and plentiful, meaning they are preserved well as fossils, and their bumps and ridges can be used to identify both present-day and ancient mammals. 

When the researchers examined the specimens’ teeth and jaws, they found distinctive features suggesting they were looking at three previously unrecognized species. To find out where these creatures fell in the ungulate family tree, the team compared the fossils to teeth from 25 other condylarths and another more distantly-related early mammal. They analyzed 64 characteristics of each specimen’s teeth and used a computer program to determine how closely related their mammalian owners were. 

This analysis confirmed that the three new species fell within a family called the periptychids. This family had bulbous cheek teeth, in some cases with striated enamel that would have strengthened the tooth and perhaps enabled the animal to eat hard materials such as seeds.

[Related: This Australian behemoth is officially the largest dinosaur on the continent]

One of the new species was stuck out. Beornus honeyi would have been roughly the size of a housecat and had strikingly large striated cheek teeth. (Its name is a reference to Beorn, a character from J.R.R. Tolkien’s The Hobbit, and who is known for his massive size.)

“Periptychids all have these puffy teeth, but Beornus is above and beyond,” says Atteberry, a geologist and undergraduate program assistant at the University of Colorado Boulder. “They look like they were stung by little bees; they’re very swollen-looking.” 

The other new species were likely between a rat and housecat in size. Miniconus jeanninae was distinguished by an unusual extra cusp on its molars. Conacodon hettingeri is set apart from its close relatives by several features, including a comparatively short lobe on its last molar.   

While the three species boasted distinct dentition and probably had somewhat different diets, it’s not clear what they actually did eat from the shape of their teeth alone, Eberle says. Part of the reason for this is that condylarth teeth don’t generally resemble those of any living mammals. In the future, Eberle and her colleagues hope to build a better picture of what the mammals might have feasted on by looking at wear patterns on the teeth, such as little pits and scratches that would indicate that an animal had dined on seeds or other crunchy things.

The specimens Eberle and Atteberry investigated were housed in the University of Colorado Museum of Natural History, along with more than 400 others from the same site. 

“I would predict that there’s a number of new species still yet [to be identified] in the collection that we need to get studying,” Eberle says. “This is just the beginning.”

The new findings highlight how quickly mammals began to bounce back after the cataclysmic asteroid strike, says Nick Longrich, a paleontologist at the University of Bath in England who was not involved with the research. 

These early mammals would have faced little competition and evolved to fill ecological roles vacated by the dinosaurs. “You’re seeing this incredible burst of creativity of the mammals, kind of in response to this disaster,” Longrich says. “It doesn’t surprise me at all that there’s much more happening much faster than we thought.”

The discovery of three new species not seen anywhere else also demonstrates how different locations might have developed unique pockets of diversity.

“It’s not a monotonous wasteland but a sort of diverse set of post-apocalyptic landscapes,” Longrich noted in an email. “Imagine if, for example after the world ends, it’s a zombie apocalypse in one area, Mad Max bikers in another region, cannibal cult in another, and so on.”

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A new species of pterosaur has been discovered, a flying reptile that once graced the skies of the Australian Outback around 105 million years ago. The imposing, dragon-like creature, Thapunngaka shawi, was named to reflect its extremely pointy teeth in the now-extinct language of the local Indigenous Wanamara tribe. 

In 2011, a local fossil hunter discovered a portion of what looked to be a lower jaw. Upon examination, paleontologists realized that this was a new, rather impressive species of Australian pterosaur. Their analysis showed that this winged reptile must have had a skull longer than three feet, and a wingspan of about 30, making it the largest Australian pterosaur discovered to date. They published their findings in the Journal of Vertebrate Paleontology. 

Before University of Queensland paleontologist and lead author Tim Richards properly examined Thapunngaka shawi, the fossil stayed on display in Kronosaurus Korner, a local museum. “It had a sign on it which just said ‘Pterosaur – indeterminate,’” Richards told Brisbane Times. But “I realized once I started looking at it closely that it had features I’d never seen before and I wondered if it could be something new,” he added. “Lo and behold, it was.”

[Related: This Australian behemoth is officially the largest dinosaur on the continent]

While Australia has been the site of many dinosaur discoveries, it’s still fairly new to the pterosaur game, which represents a branch of prehistoric animals related to but still distinct from dinos. The continent’s first specimen was discovered just 40 years ago, and only 20 specimens have been identified to date. Richards told Australia’s ABC News that “by world standards, the Australian pterosaur record is poor but the discovery of Thapunngaka contributes greatly to our understanding of Australian pterosaur diversity.”

Although Thapunngaka shawi’s 30-foot wingspan is nothing to scoff at, it’s certainly not the largest pterosaur to have ever lived on Earth. The Transylvanian “Dracula” pterosaur, which lived between 240 and 66 million years ago, had a wingspan of almost 40 feet. A Texan pterosaur discovered in the 1970s had an estimated wingspan of more than 50 feet. 

A new pterosaur discovery is exciting because “it’s the closest thing we have to a real-life dragon,” said Richards in a statement. They were “a successful and diverse group of reptiles—the very first back-boned animals to take a stab at powered flight.”

And Thapunngaka shawi was definitely a fearsome predator. “It was essentially just a skull with a long neck, bolted on a pair of long wings,” Richards added. “This thing would have been quite savage. It would have cast a great shadow over some quivering little dinosaur that wouldn’t have heard it until it was too late.”

In naming their new pterosaur species, the researchers wanted to honor the local First Nations Wanamara people. The word “thapunngaka” combines thapun [ta-boon] and ngaka [nga-ga], which are Wanamara for “spear” and “mouth,” respectively. “Shawi” is taken from the name of the fossil’s discoverer, Len Shaw. Together, the species name means “Shaw’s spear mouth.”

Correction 8/10/2021: Due to an editing error, a previous headline for this story named the species as a dinosaur, when, in fact, it is an ancient reptile.

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A remarkably preserved skull from a small, gull-like creature called Ichthyornis may shed light on how the ancestors of modern birds weathered the mass extinction that killed off all the other dinosaurs. 

Scientists compared the Ichthyornisin skull to those of dozens of living birds. They found that this close relative of today’s birds nonetheless had a brain whose shape was distinctly different. The findings indicate that the expanded forebrains found among living birds helped them adapt to a rapidly changing world, the researchers reported on July 30 in Science Advances.

“A unique brain shape, specifically a really large cerebral hemisphere, was a major factor in why living birds were able to survive when no other dinosaurs could,” says Christopher Torres, a paleontologist at Ohio University in Athens and coauthor of the findings.

When an asteroid more than six miles wide smashed into Mexico’s Yucatán Peninsula 66 million years ago, it triggered tsunamis and wildfire and kicked up a blanket of dust that circled the planet and blocked the sun’s light, causing plants to die and dramatically altering Earth’s climate. Yet some ancient birds survived the catastrophe, and scientists have proposed several ideas about which traits might have given them an edge. 

[Related: This Australian behemoth is officially the largest dinosaur on the continent]

One possibility is that these birds were smaller, and thus more adaptable, than their neighbors. “How much food an organism needs to eat, how it can travel, where in the world it can live, what latitude it can live at, all of these traits are linked to body size,” Torres says.

Or perhaps the answer lies in the toothless beaks seen in today’s birds, which could dine on a range of foods, from flesh to seeds. 

Present-day birds also have very complex brains. “They’re incredibly smart creatures, and so it’s been proposed that some aspect of the brain and what the brain can do may have contributed to that unique survivorship,” Torres says.

Unfortunately, though, very little is known about the brains of early birds. As a group, they are relatively small and have fragile bones. The process of fossilization is “unimaginably brutal,” Torres notes, and the few skulls that withstand it tend to wind up flattened and difficult to decipher. 

But Archaeopteryx, the earliest recognized bird which lived 150 million years ago, is an exception. Scientists have been able to determine that its forebrain was proportionately much smaller than those of living birds. 

The 70-million-year-old Ichthyornis skull Torres and his colleagues examined may fill in some of the gaps between Archaeopteryx and living birds. Ichthyornis was a pigeon-sized seabird with a toothed beak that dwelled in present-day North America. It’s also one of the closest-known relatives of living birds. This means Ichthyornis can help researchers narrow down which traits were truly unique to the bird lineages that survived the asteroid’s aftermath. 

Torres and his team used CT scans of the nearly complete skull, originally discovered several years ago by collectors in Kansas, to digitally reconstruct the general shape of Ichthyornis’s brain. The researchers then compared this brain to similar analyses of Archaeopteryx, several more distantly-related dinosaurs, and dozens of living birds including flamingoes, woodpeckers, penguins, ostriches, and robins. 

In living birds the cerebrum, a part of the forebrain made up of a left and right cerebral hemisphere, is very large relative to the rest of the brain. This region is where higher cognition occurs, including the processing of sensory information, memory, and more. 

To accommodate its impressive size, the cerebrum is also positioned differently in birds compared with other reptiles such as snakes and crocodiles. Modern birds have a cerebrum that sits atop, rather than directly in front of, the midbrain.

Torres and his colleagues found that Ichthyornis, despite its evolutionary proximity to living birds, had a brain that was much more similar to that of Archaeopteryx. Its cerebrum was still fairly small and its brain had an overall more linear shape. The bulky cerebrum, the results suggest, didn’t become really pronounced until the modern birds emerged. 

It’s not clear precisely what advantages these expanded forebrains gave these birds, Torres says. However, as conditions deteriorated in the wake of the asteroid, he says, “their ability to process those changes and react accordingly, and quickly enough, could have made all the difference when it came to surviving this mass extinction event.”

That said, brain size probably wasn’t the only reason that the ancestors of today’s birds survived. Their small bodies, beaks, and other traits may have also contributed, Torres says. The researchers did attempt to estimate the impact of body size by analyzing measurements from more than 2,000 extinct and living species. However, they felt they didn’t have enough information on the body sizes of other birds that lived at that time to properly determine if size played a role in survival. 

Additionally, he cautions, the researchers could only draw upon data from the skulls of two ancient bird species.

“We still don’t know what the brain looked like in most early birds,” Torres says. He hopes that more well-preserved fossils like that of Ichthyornis will be unearthed in the future. “That’s really going to help us fine tune this picture and better understand what it is that made living birds so special.”

As a next step, the researchers will examine living birds to understand how much the cerebrum varies among members of the same species. This in turn will help determine how well the few available Ichthyornis and Archaeopteryx skulls actually represent these long-gone birds.

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Last week, researchers from Brazil published an article in the Journal of South American Earth Sciences updating the world on the state of dinosaur trace fossils in Brazil. But they’re not just any trace fossils; these are the fossilized remains of the remains of a dinosaur’s dinner: feces and urine.

Fossilized feces are called coprolites and are not uncommon. You can buy coprolite jewelry on Etsy and a (potentially mis-identified) six-million-year-old coprolite sold at auction for $10,370 earlier this year.

Unlike feces, liquid urine doesn’t get preserved for millions of years. But the impression of a high-powered stream of dinosaur pee hitting soft sand can be preserved. Those impressions are called urolites, and they look like this:

Urolites

Imagine you briefly turn on a hose and fire it at soft soil or sand. You’ll probably create a deeper hole where the water initially hits, and then a shallower, narrower, area as the liquid flows away. That’s the shape that these urolites have. When the researchers originally published a study on the Brazillian urolites back in 2004, they looked to a modern animal to explain their distinctive shape. It turns out that ostriches pee (video, if you are so inclined) in a similar way, letting out a stream of liquid waste that hits the ground at a fairly high speed, followed by their solid waste, separately.

It’s a fascinating idea, but scientists are still trying to figure out if that’s actually how dinosaurs pee.

“The question,” Brian Switek wrote on his Laelaps blog earlier this year “is whether non-avian dinosaurs expelled their solid and semi-solid waste together, like many birds, or they urinated and defecated separately as ostriches and crocodylians can.”

Figuring out how dinosaurs excreted their excrement still requires more research — and more fossils. But those aren’t easy to come by. The urolites in Brazil are among the few dinosaur-associated urolites in the world. The scientists in Brazil are concerned about the preservation of the coprolites and urolites, writing in their conclusions that their work collecting specimens is being hampered by mining and ranching operations near the location of the fossils, which they refer to as a “natural treasure.”

I think we can all agree that it’s a fairly impressive description for something that started out as… well… crap.

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The 3-foot-long Microraptor, one of the smallest dinosaurs in the fossil record, had feathers on its arms, legs and tail. Its odd-looking five-wing gliding setup provides clues to the earliest evolution of flight, according to a new study in Nature Communications.

Dinosaur In The Wind

To figure out how exactly Microraptor might have flown, a team of scientists from the University of Southampton in the UK designed an anatomically accurate model and tested its abilities for stability and speed in a wind tunnel. The early Cretaceous dinosaur was a paravian–a classification of dinosaurs that were closer to birds than species like the T. Rex.

Studying The Evolution Of Flight

In the wind tunnel, the blue 3-D model of a Microraptor showed that the dinosaur probably would have flown down from the trees and glided slowly across medium distances. The dinosaur would have been most stable by generating a great deal of lift with its wings, but the exact positioning and angles of the wings, which haven’t been determined, didn’t make much of a difference–small changes in the shape and orientation of the wings and legs didn’t change how well the model flew. The researchers write that this suggests early fliers like Microraptor “did not require a sophisticated, ‘modern’ wing morphology to undertake effective glides.”

See part of the wind tunnel test in the video below:

The study is published in Nature Communications today.

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When you imagine a dinosaur’s habitat like that you would see in Jurassic Park, a hot and humid spot filled with verdant greenery might come to mind. However, a growing body of evidence points to these prehistoric reptiles romping around in much chillier climates—as far north as the Arctic.

Researchers discovered hundreds of teensy tiny baby dinosaur bones in Northern Alaska, suggesting polar dinosaurs lived in high latitudes year-round. They published their findings this month in Current Biology.

“It wasn’t long ago that people were surprised dinosaurs could live in the Arctic at all, and now we know they’re actually reproducing there,” Patrick Druckenmiller, lead author and director of the University of Alaska Museum of the North, says. “And that just has a whole bunch of mind-blowing consequences as far as how dinosaurs lived and what types of adaptation they had.”

Discovery of cold weather Cretaceous creatures

Researchers discovered the first fossilized remains of Arctic and Antarctic dinosaurs in the 1950s. Before then most paleontologists believed the environmental conditions—think months of darkness and snow—would have been too severe for reptiles to thrive in. 

Upon finding the frost-loving dinos, paleontologists put forth two explanations. The first posited the creatures spent their whole lives in the tundra. But a second theory predicted herbivorous dinosaurs migrated north as temperatures warmed and leafy-greens sprouted through thawing ground. Trailing their prey, carnivorous dinosaurs followed, and as wintry weather arrived, both herbivores and carnivores followed their food southward again.

To quite literally dig up the truth, Druckenmiller and his team spent three decades unearthing evidence at their field site in Northern Alaska. The fossil-rich spot, known as the Cretaceous Prince Creek Formation (PCF), is located along the bluffs of the Colville River as it merges with the Arctic ocean, and is one of the best locations in the world to study polar dinosaurs. 

To reach the paleontological goldmine in the depths of rural Alaska, the scientist spent three to five days traveling by car, helicopter, and boat. Then, they would pitch camp along the gravelly banks for three weeks. 

“This was really a labor of love,” Druckenmiller, who spent many a night wet, muddy, and blasted with freezing sea breeze, says.  

[Related: These ancient deep-sea fish can live five times as long as biologists expected]

Digging up baby dinos 

At the formation, the researcher found small bones—many of which were too tiny to belong to your ordinary small-bodied beast. 

“Once we started to see really small teeth and really small bones that showed features of very, very young animals it started to gradually dawn on us that maybe these aren’t just small species of dinosaurs, maybe these are babies,” Druckenmiller said. 

The researchers were soon re-filling their food buckets with pounds of sediment to bring back to the lab, where they would screen the sand through sieves. Every grain larger than half a millimeter under a microscope—that’s one-third the size of a pinhead—was closely inspected. 

What they discovered was thousands of teeth. When compared to similar dinosaurs from other parts of the world, they found the teensy teeth didn’t just belong to baby dinos. Some were so small they could only come from perinatal dinosaurs, those who die while still in the egg or just after hatching. They matched the pearly whites to a variety of both herbivorous and carnivorous species like duck-billed, horned, and dome-headed dinosaurs. Even fearsome tyrannosaurids had hatched amongst the snow. 

“We now understand that dinosaurs were not only living way up in the polar regions, which is remarkable in itself, but that they were also reproducing up there. And if they were reproducing up there, it strongly implies that they were spending their entire lives living in the arctic,” Druckenmiller said. 

The eggs of these bygone animals took two to six months, maybe even longer, to hatch. Therefore, if their mothers popped them out at the dawn of spring, the hatchlings only had a few months to grow before winter set in. Thus, a thousand mile migratory trek would be out of the question. 

Reimaging dinosaurs—and their habitats 

Knowing dinosaurs spent their whole lives at the poles means paleontologists have to reconfigure their understanding of them. 

In order to survive 120 days of continuous darkness and an average temperature of 43 degrees Fahrenheit, the circumpolar creatures were most likely warm-blooded. They could have even been decked out in fuzzy feathers like gigantic, ancient snowy owls to keep warm. 

“One idea is maybe dinosaurs hibernated,” Druckenmiller says, “and there’s no reason why we might not actually find something like a dinosaur borough that some of the smaller species may have snuggled up in for the winter.” 

Regardless, the findings conjure an alternate universe where down-covered dinosaurs scampered through snow-covered forests. 

“It just makes you realize what a different world it was 70 million years ago, that Alaska, which was even farther north at the time, supported forests, and in those forests were crazy dinosaurs running around, trying to struggle their way through winter,” Druckenmiller said. “It’s mind-blowing.”

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Allosaurus

For 165 million years, dinosaurs dominated land, sea, and sky. Long-necked Brachiosauruses lumbered along like mobile four-story buildings. Tyrannosaurus rex chased down prey with 50 to 60 teeth as big as bananas. Mosasaurs stretching 55 feet from snout to tail terrorized the seas, consuming everything they could catch.

But 66 million years ago, the world’s climate drastically changed. Dinosaurs had thrived in the warm temperatures and mild weather of the Mesozoic era. All of a sudden, the Earth became much colder and darker. Plants died and food became scarce. All the dinosaurs—except for the ancestors of modern birds—and three quarters of the creatures living on Earth went extinct.

To this day, scientists debate what caused this sudden change. The leading theories involve an asteroid strike and a giant volcano.

Both theories start with a rare metal called iridium. This element is extremely rare on our planet’s surface, but does exist in Earth’s liquid core and in space rocks like asteroids. In the rock underneath the Earth’s oceans and continents, there’s a thin iridium layer in what geologists call the K-T Boundary, or the point in the geologic record where they see evidence of the dinosaurs’ mass extinction.

Discovering this layer led scientists to speculate that a giant, six-mile-wide meteor hit the Earth around 66 million years ago. The impact had the force of 10 billion nuclear bombs and would have thrown massive clouds of iridium dust and other debris into the air, blocking out the sunlight for years.

Researchers discovered an enormous crater in the Yucatan Peninsula in Mexico that may have been in just the right spot to cause maximum destruction, as the rocks in this area may have been especially rich in carbon dioxide and sulfur or hydrocarbons, all of which could have been released into the air upon impact and contributed to the rapid shift in the climate. The crater was also around 66 million years old. Scientists found some other strange clues in the ancient layers: shocked quartz, rock that looks like a massive shockwave rearranged its crystals; soot that suggested widespread wildfires; and glass-like spheres that looked like cooled molten rock.

While many scientists think a giant fireball signaled the end for the dinosaurs, not everyone is convinced. Some say the iridium layer and the strange rock clues could also point to volcanic activity instead.

Volcanoes went wild during the last 40 million years of the dinosaurs’ reign. In what is now western India, giant cones belched lava drawn up from the Earth’s mantle, spewing dust and ash. After millions of years of eruptions, scientists reason there could have been enough debris in the air to block out the sun. The volcanoes also could have drawn iridium from deep within the Earth to form the thin layer we see in the crust today.

Some scientists argue the volcanoes would not have changed the climate drastically enough to kill all the dinosaurs. Others say the truth could be a combination of these two theories. The asteroid could even have made the eruptions worse, giving the dinosaurs a geologic one-two punch. Other scientists think the dinosaurs had already started gradually dying off before something catastrophic finished them off.

Whether by asteroid or volcano, we do know the whole planet changed suddenly and drastically. And when the darkness lifted, the surviving mammals, reptiles, and birds took over the planet.

This story has been updated to reflect the fact that the theorized impact of the asteroid collision was along the lines of 10 billion nuclear bombs, not 10 nuclear bombs, as previously stated. We regret the error.

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What was once thought to be the smallest dinosaur ever found has now been confirmed to be a lizard.

In March 2020, a Nature paper stirred some controversy when scientists identified a skull encased in 99 million year old Myanmar amber as that of a tiny, bird-like dinosaur. The authors dubbed the specimen Oculudentavis khaungraae, and acknowledged the strangeness of the fossil—most notably, they found the shape of the bones, especially around the eye region, didn’t seem to follow other bird or dinosaur evolutionary patterns.

Following publication, other paleontologists refuted the paper’s findings. Another team of scientists published a preprint in bioRxiv in June of 2020, stating that the skull more closely matched one of a lizard. The Nature paper was retracted in July of 2020. Released as a preprint in August 2020, and now as a fully peer-reviewed study in Current Biology, another study by a third team of scientists confirms that Oculudentavis is a lizard genus. 

The new paper is based on another, better preserved specimen—a fossil also from Myanmar, whose skull is about a half an inch long, and also around 99 million years old. Using CT scans and 3D remodeling, the authors concluded that their fossil was a different species in the same genus as O. khaungraae—they called their specimen Oculudentavis naga—and that both species were indeed strange lizards rather than small dinosaurs. 

“It’s a really weird animal. It’s unlike any other lizard we have today,” Sam Houston State University herpetologist and study co-author Juan Diego Daza said in a statement. He added that the Cretaceous Period, when these fossils were formed, was when many lizard and snake groups emerged, but “they still hadn’t evolved their modern appearance,” which explains why identifying these fossils can be so challenging. “That’s why they can trick us. They may have characteristics of this group or that one, but in reality, they don’t match perfectly.”

[Read more: This Australian behemoth is officially the largest dinosaur on the continent]

The way the amber fossils were preserved distorted the skulls of both Oculudentavis specimens, which contributed to the original misunderstanding. O. khaungraae’s snout was distorted into a narrower cone shape, giving a birdlike impression, while O. naga’s upper skull was likely flattened during fossilization to appear more lizard-like. 

The genus name Oculudentavis, established by the authors of the first Nature paper, means “eye tooth bird” in Latin. Even though that name is technically inaccurate now, Daza told CNN that taxonomic rules for naming and organizing animal species dictate that they have to continue using it. “Since Oculudentavis is the name originally used to describe this taxon, it has priority and we have to maintain it,” Daza said. “The taxonomy can be sometimes deceiving.”

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After 15 years of analysis, scientists have finally confirmed the discovery of Australia’s largest known dinosaur species. 

The first remnants of Australotitan cooperensis were found in 2006 near Eromanga in southwest Queensland, Australia, by Robyn Mackenzie, a paleontologist at the Eromanga Natural History museum, on her own property. She and her husband nicknamed the then-unknown dinosaur “Cooper,” after Cooper Creek near the discovery site. They then called in collaborators to complete the excavation. 

The team unearthed thousands of pounds of bones.

But just digging up the fossils wasn’t enough. The real investigation came after. Based on the bones they collected, the team suspected that this dino was a sauropod, a type of dinosaur previously found in the area (well known sauropods include the brontosaur and the brachiosaurus). But in order to identify just what species Cooper was, scientists needed to methodically compare their found bones to those of previously described species. 

“It’s taken this long because it’s such a painstaking piece of work, you’ve got to take the bones out of the ground, you’ve got to prepare the fossils, and then you’ve got to study them and compare them against all other species of dinosaurs worldwide,” Queensland Museum palaeontologist and co-author of the study Scott Hocknull told Australia’s ABC News.

Rather than cart cumbersome loads of fossils around the world, the team turned to 3D scanning technology for analysis. “[It] allowed us to virtually carry thousands of kilograms of dinosaur bones in one seven kilogram laptop,” Hocknull wrote in The Conversation. 

Not only did the researchers find that Cooper was not a member of any previously described species, they also officially deemed the Australotitan dinosaur, or the “southern titan,” to be the largest known dinosaur to ever roam the outback. It likely weighed somewhere between 25 and 81 tons. At about 80 to 100 feet long and 16 to 21 feet tall at its hip, Australotitan is also within the top 10 to 15 largest dinosaurs in the world. For comparison, the Tyrannosaurus rex was only about 40 feet long and 12 feet tall. 

With those stats, Cooper joins the ranks of the titanosaurs, a group of mega-beasts previously only discovered in South America. It lived between 92 million to 96 million years ago. The findings were published in the journal PeerJ. 
Mackenzie told ABC News that Australotitan was just “the tip of the iceberg” and that there are plenty of Australian sites brimming with potential for more fossil excavations. Australotitan was a plant eater, Hocknull noted, “so what was marauding around trying to eat these guys? We don’t have any evidence of that just yet.” Each discovery will help complete the story of Australia’s ancient past.

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In the age of dinosaurs, a succession of mega carnivores lorded over the landmass that is now North America. First came the 30-foot-long Allosaurus, 145 million years ago. Sixty million years later, the 40-foot-long T. rex reigned supreme. But scientists didn’t know what, or who, prevented T. rex from taking the throne during the intervening period. That is, until paleontologists from the Field Museum and North Carolina State University, on a dig in Utah, unearthed bones from the leg, tail, and spine of an all-new species. The researchers dubbed the dino Siats meekerorum after a man-eating monster in local Ute legend. The beast would have rivaled T. rex in size and power had the two coexisted. But only after Siats went extinct could tyrannosaurs, then the size of white-tailed deer, evolve into fearsome T. rex and assume the role of apex predator.

Other Nightmarish New Species

By Jessie Geoffray

The Chicken from Hell

Paleontologists from the University of Utah announced the discovery of this 11-foot-long dinosaur in March. The 500-pound raptor is the largest known oviraptorosaur—a group of dinos closely related to birds—found in North America. Anzu wyliei roamed the Dakotas with T. rex about 66 million years ago, just before dinosaur end-times.

Mouth Full of Switchblades

In Portugal, paleontologists uncovered what may be Europe’s largest known terrestrial predator. Torvosaurus gurneyi ruled the continent during the Jurassic Period 150 million years ago. It weighed in at 2,200 pounds, and stretched 33 feet from snout to tail. Some of its blade-shaped teeth measured nearly four inches long.

Polar Half-Pint

Nanuqsaurus hoglundi, a new tyrannosaur recently found by Texas paleontologists, is believed to have lived some 70 million years ago in the region that’s now Alaska. The pygmy dinosaur, whose name translates to “polar bear lizard,” was only half the length of its domineering cousin, T. rex, and 1/15 its weight.

An artist’s rendition of the 500-pound “Chicken From Hell”

This article originally appeared in the September 2014 issue of Popular Science.

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Lars Schmitz is an associate professor of biology at Scripps College; Jonah Choiniere is a professor of dinosaur paleontology at the University of the Witwatersrand; and Roger Benson is a professor of Palaeobiology at the University of Oxford. This story originally featured on the The Conversation.

Today, barn owls, bats, leopards and many other animals rely on their keen senses to live and hunt under the dim light of stars. These nighttime specialists avoid the competition of daylight hours, hunting their prey under the cloak of darkness, often using a combination of night vision and acute hearing.

But was there nightlife 100 million years ago? In a world without owls or leopards, were dinosaurs working the night shift? If so, what senses did they use to find food and avoid predators in the darkness? To better understand the senses of the dinosaur ancestors of birds, our team of paleontologists and paleobiologists scoured research papers and museum collections looking for fossils that preserved delicate eye and ear structures. And we found some.

Using scans of fossilized dinosaur skulls, in a paper published in the journal Science on May 6, 2021, we describe the most convincing evidence to date for nocturnal dinosaurs. Two fossil species—Haplocheirus sollers and Shuvuuia deserti—likely had extremely good night vision. But our work also shows that S. deserti also had incredibly sensitive hearing similar to modern-day owls. This is the first time these two traits have been found in the same fossil, suggesting that this small, desert-dwelling dinosaur that lived in ancient Mongolia was probably a specialized night-hunter of insects and small mammals.

Looking to theropods

By studying fossilized eye bones, one of us, Lars Schmitz, had previously found that some small predatory dinosaurs may have hunted at night. Most of these potentially nocturnal hunters were theropods, the group of three-toed dinosaurs that includes Tyrannosaurus rex and modern birds. But to date, fossils for only 12 theropod species included the eye structures that can tell paleontologists about night vision.

Our team identified four more species of theropods with clues for their sense of vision—for a total of 16. We then looked for fossils that preserve the structures of the inner ear and found 17 species. Excitingly, for four species, we were able to get measurements for both eyes and ears.

Eye bones built for night vision

Scleral ossicles are thin, rectangular bone plates that form a ring-like structure surrounding the pupils of lizards as well as birds and their ancestors—dinosaurs. Scleral rings define the largest possible size of an animal’s pupil and can tell you how well that animal can see at night. The larger the pupil compared to the size of the eye, the better a dinosaur could see in the dark.

Since the individual bony ossicles of these rings fell apart after these animals died more than 60 million years ago, our team made scans of the fossils and then digitally reconstructed the eyes. Of all the theropods we examined, H. sollers and S. deserti had some of the proportionally largest pupils.

S. deserti‘s pupil made up more than half of its eye, very similar to night-vision specialists that live today like geckos and nightjars. Our team then compared the fossils to 55 living species of lizards and 367 species of birds with known day or night activity patterns. According to the statistical analyses our team performed, there is a very high chance—higher than 90 percent—that H. sollers and S. deserti were nocturnal.

But those were not the only two theropods our team looked at. Our analysis also found a few other likely nighttime specialists—such as Megapnosaurus kayentakatae—as well as daylight specialists like Almas ukhaa. But we also found some species—like Velociraptor mongoliensis—with eyesight seemingly adapted for medium light levels. This might suggest that they hunted around dawn or dusk.

Incredible ears of a dinosaur

In today’s nocturnal animals, hearing can be as important as keen eyesight. To figure out how well these extinct dinosaurs could hear, we scanned the skulls of 17 fossil theropods to decipher the structure of their inner ears and then compared our scans to the ears of modern animals.

All vertebrates have a tube-like canal called the cochlea deep in their inner ear. Studies of living mammals and birds show that the longer this canal, the wider the range of frequencies an animal can hear and the better they can hear very faint sounds.

Our scans showed that S. deserti had an extremely elongated inner ear canal for its size—also similar to that of the living barn owl and proportionally much longer than all of the other 88 living bird species we analyzed for comparison. Based on our measurements, among dinosaurs, we found that predators had generally better hearing than herbivores. Several predators—including V. mongoliensis—also had moderately elongated inner ears, but none rivaled S. deserti’s.

The life of a nocturnal dinosaur

By studying the sensory abilities of dinosaurs, paleontologists like us not only are learning what species roamed the night, but can also begin to infer how these dinosaurs lived and shared resources.

S. deserti had extreme night vision and sensitive hearing, and this little dinosaur probably used its incredible senses to hunt prey at night. It could likely hear and follow rustling from a distance before visually detecting its prey and digging it up from the ground with its short single-clawed arms. In the dry, desert-like habitats of millions of years ago, it might have been an evolutionary advantage to be active in the cooler temperatures of the night.

But according to our analysis, S. deserti wasn’t the only dinosaur active at night. Other dinosaurs like V. mongoliensis and the plant-eating Protoceratops mongoliensis both lived in the same habitat and had some level of night vision.

Paleontologists currently do not know the full suite of animals that shared S. deserti’s extreme nocturnal lifestyle in the ancient deserts of Mongolia—it is rare to find fossils with the right bones intact that allow paleontologists to investigate their senses. However, the presence of a specialized night forager highlights that much like today, some dinosaurs avoided the dangers and competition of daylight hours and roamed under the stars.

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Tyrannosaurus rex was the apex predator of the Cretaceous period, around 66 to 68 million years ago. But scientists had never calculated the total number of T. rexes there ever were—until now. A new study estimates that about 2.5 billion of these tyrannical dinosaurs roamed the Earth over all of history, a stunning “absolute abundance” for these absolute units.

Only about 20,000 Tyrannosaurus rexes were alive at any given time. But these fearsome Goliaths occupied North America for an incredibly long span, between 1.2 and 3.6 million years. That means that approximately 127,000 generations of T. rexes passed through this Earthly plane, leading scientists to that 2.5 billion estimation. 

“That’s a lot of jaws,” lead author Charles Marshall told the AP. Marshall is the director of the Museum of Paleontology at the University of California. “That’s a lot of teeth. That’s a lot of claws.”

[Related: The biggest animal ever to fly was a reptile with a giraffe-like neck]

This number is the first of its kind, but it’s in no way a definitive answer. Rather, 2.5 billion is an estimate with a wide margin of error. The total population could have been anywhere from 140 million to 42 billion. 

All this uncertainty stems from the fact that scientists are operating with a lot of unknowns. To reach their T. rex count, scientists first had to compile the existing research on the king of tyrant lizards. The best estimates suggest each T. rex lived about 28 years. With sexual maturity arriving at roughly 15.5 years, the authors calculated a generation time of about 19 years.

Ecologists also know that the bigger an animal is, the smaller its population density tends to be. Using existing formulas to model that relationship—and the fact that a fully grown T. rex likely weighed about 15,000 pounds—the paper authors concluded that there was roughly one T. rex for every 42 square miles. That translates to about 3,800 T. rexes in an area the size of California, or just two individuals in a place like Washington, D.C, the study says. 

If the 2.5 billion total population statistic is accurate, then only one out of every 80 million Tyrannosaurus rexes made it into the fossil record. 

If the total were 2.5 million, instead of billion, Marshall said, we might never have discovered T. rex at all.

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Flying lizards with giraffe-like necks and wing spans up to nearly 40 feet once ruled the skies while dinosaurs roamed below. These impressive albeit bizarre beasts, the azhdarchid pterosaurs, lived from the Late Triassic period until near the end of the Cretaceous period, and are the largest known vertebrates to ever take flight. 

Scientists have long wondered how these ancient lizards could support their heads—their bones, like those of most birds, are quite lightweight and fragile. Especially if they were carrying prey in their mouths, the weight of the skull would be quite difficult to hold up with such a long, thin neck. But new research published this week in iScience shows that these animals had unique bone structure: Their vertebrae had fine struts that extended from a central neural tube out to the vertebra wall, similar to the spokes of a bicycle. The effect is a helix-like structure of support.

“It is unlike anything seen previously in a vertebra of any animal,” paleobiologist and co-author David Martill said in a statement. “This structure… resolved many concerns about the biomechanics of how these creatures were able to support massive heads—longer than 1.5 meters—on necks longer than the modern-day giraffe, all whilst retaining the ability of powered flight.”

Martill and his team made this discovery by examining azhdarchid pterosaur fossils from the Kem Kem site in Morocco—a fossil-rich area, and one of the only places you can find relatively intact Azhdarchid specimens. They placed pterosaur vertebrae through a CT scan, and they were amazed by the structures they found inside. 

With the help of biomechanical engineers, they then assessed just how helpful the spoke-like structures were for easing the flying reptiles’ neck strain. Their analyses found that just 50 of these struts (with limited fossil records it’s hard to be sure exactly how many each creature had) increased their weight-bearing capacity by 90 percent, which explains how these ancient lizards could be such strong fliers and fierce predators without breaking their own necks. 

Neck strength could have also been important to these pterosaurs for “neck bashing,” a type of rivalry-driven ritual between males that giraffes engage in today. 

Knowing the structure of these vertebrae will help scientists gain more accurate understanding of azhdarchid pterosaurs—from how they moved, to the prey they might have been able to catch, and how big they really could have gotten. 

Regardless, the never-before-seen neck vertebrae structure is quite a discovery, Martill said, and shows how “evolution shaped these creatures into awesome, breathtakingly efficient flyers.”

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A newly discovered species of dinosaur likely ruled ancient South America in the dinosaurs’ twilight period, using its massive claws, powerful bite, and sharp teeth to earn its name “the one who causes fear.”weir

Paleontologists discovered the superbly-preserved skull of the new species in a famous fossil site called the Baja de La Carpa Formation in Northern Patagonia, Argentina. It gives insights into the biodiversity of the late Cretaceous period, about 85 million years ago, the last and longest period of dinosaurs, according to a new study published in the Journal of Vertebrate Paleontology.

The new dinosaur has been dubbed Llukalkan aliocranianus; “llukalkan” meaning “the one who causes fear” in the Mapuche language indigenous to the region, and “aliocranianus” meaning “different skull” in Latin. The species reached about 16 feet in length and belonged to a diverse group of dinosaurs called abelisaurids.

Quite unusually, the remains of the L. aliocranianus were discovered less than half a mile from the remains of another similarly sized, meat-eating dinosaur from the same time period, the Viavenator exxoni. This close proximity suggests a complex and unusual structuring of ecosystems between the top predators, where the two species likely went after the same prey—and maybe even each other.

“It is likely that these dinosaurs shared the same ecological niche and fed on the same type of prey, so they would have competed with each other and, why not, even eaten with each other,” said study co-author Ariel Méndez in an email. “This would not be very different from what is observed today, where predators of different species but of the same family coexist in the same ecosystem, such as lions, leopards and cheetahs.”

[Related: This fossilized butthole gives us a rare window into dinosaur sex]

Though paleontologists dug up the bones in present-day Argentina, when the dinosaurs were around to roam the land it was part of Gondwana, the ancient southern subcontinent that formed when Pangea split and included much of today’s southern hemisphere like Australia, Antarctica, and the Indian subcontinent. The abelisaurids were likely the top predator of Gondwana in the era, sitting comfortably atop the food chain just as the well-known Tyrannosaurus Rex’s did in the northern continent. 

“Certainly, finding yet another species of abelisaurids in that late Cretaceous time period we can say, ‘Ok, they really were the dominant taxa,’” says Peter Makovicky, a paleontologist and professor at the University of Minnesota who was unaffiliated with the study. “[This] in turn tells a bit about biogeography [on] Gondwana, the southern continent. You look at the northern continent, it’s the tyrannosaurs that are doing that, stepping in and showing out in the top predator niche.”

A unique feature of L. aliocranianus compared to other members of its group is an air-filled pocket next to the ear entering the skull that would have given the species superior hearing abilities, comparable to the modern-day crocodile’s, who have excellent auditory range and are just as chatty as birds. This confirms that L. aliocranianus was a predator rather than a scavenger, according to study co-author Rubén Juárez, since it used the adaptation to listen for living prey. 

Paleotontoglists want to focus future research on gathering more fossils to better understand these complex ecosystems, investigate the difference between male and female abelisaurids, and learn more about how quickly the species matured into full-sized predators. 

“Understanding how long they spent at different sizes throughout their growth and development could also help us understand how you can pack multiple species into one ecosystem,” Makovicky says. “That’s one thing we really don’t have a grasp on yet.” 

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If you went back in time 120 million years, the majority of the birds flying overhead would be part of the now-extinct group known as Enantiornithes. These creatures looked a lot like the visitors at our feeders today, but with toothy smiles and claws on the tips of their wings. Their diets, however, are still somewhat of a puzzle.

As the most abundant and diverse group during the early Cretaceous period, these ancient birds make up almost 75 percent of the feathered fossils found in northwestern China over the past century. But in spite of all the evidence, it’s been hard to analyze the stomach contents because they don’t preserve so well. A paper published in Frontiers in Earth Science this month sheds light on Enantiornithes’ feeding habits—and provides a path forward for researching fossilized soft tissues.

The new study centers on the quartz crystals discovered in a bird from the Jehol Biota in China. Back in 2015, a researcher at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences (IVPP) concluded that a fossilized Bohaiornis guoi purposefully swallowed two rocks to help grind up food in its gut. But further comparisons with other Jehol fossils revealed that the rocks didn’t look similar enough to ones typically used to process meals.

In many cases, the discovery of preserved rocks in a fossil’s stomach indicates to researchers that the organism used small rocks to aid in the digestion of tougher foods like seeds and insects. These special stones, called gastroliths, become lodged in a section of the digestive tracts called the gastric mill. Several animals, including fish and reptiles, still exhibit this behavior. Similarly, researchers studying modern and ancient birds have found evidence of “rangle,” pebbles ingested to clear mucus and other debris from the digestive system after eating.

In light of the previous findings, Shumin Liu, lead author of the recent paper and a former graduate student at IVPP, decided to break down the composition of the stomach stones in the Bohaiornis fossil. Liu examined the samples via ground sectioning, which involves polishing the crystals thin enough to view in detail on a microscope. She also used scanning electron microscopy, a technique that sweeps the surface of the sample with a beam of electrons, to create blown-up images of the specimen. Finally, she identified the chemical composition of the rocks through energy dispersive microscopy, which excites the electrons in the molecules of a sample to elicit a telltale signal.

Doing this, Liu was able to build a profile of the stones that set them apart from preserved gastroliths in almost every way. “They’re a mineral called chalcedony, which is basically quartz that grows in sedimentary rocks,” says Jingmai O’Connor, associate curator of fossil reptiles at the Field Museum of Natural History in Chicago and one of the co-authors of the study. “Also, the traces were really thin, so it really supports that it was something that happened during formation of the fossil.” Rocks that are swallowed by a live animal maintain their round shape, even as pressure is applied over time. But the largest section of the chalcedony in the Bohaiornis guoi was flat, making it more likely that it accumulated in the bird’s skeleton after death.

It could also be that the crystals materialized from the fossil itself. “It’s very possible that the carbon is original carbon from the bird’s [soft tissue],” O’Connor says, “but it would require further analysis to test that.”

Understanding the diet of ancient creatures is important because the digestive system can offer clues about the physical abilities of the organism while it was living. This relationship is particularly intriguing in birds, O’Connor says, as it gives researchers a way to trace the development of unique structures in modern feathered species.

“Birds have a very modified digestive system because powered flight is the most physically demanding form of locomotion, so they have to reach a really high caloric demand to support this,” she explains. “Compared to all other amniotes, their digestive system has just been modified in a bunch of different ways.”

In O’Connor’s perspective, it’s strange that only a handful of Enantiornithes fossils contain ingested remains when compared to fossils from other extinct groups. But there are other pressing questions in the wake of the study she helped lead.

For instance, Ashley Poust, a postdoctoral researcher in vertebrate paleontology at the San Diego Natural History Museum, is intrigued by the origins of the chalcedony. “You go out there and you’re aiming to experimentally assess something, but in the process of disproving that, you’ve discovered a new phenomenon—the possibility of this in-place mineralization,” he says. “That’s really cool.”

[Related: How a fossilized butthole helped us better understand dinosaur sex]

Both Poust and O’Connor hope that the chemical techniques used on the Bohaiornis specimen will become more widespread for fossil analysis. “In paleontology, there is sometimes information and data that are not available just from the naked eye,” Poust says. “The fact that they approached it using a combination of observation but also these experimental methods that involve some destructive sampling is exciting.”

“We make the argument that this is what you need to do when you have very unusual traces that aren’t straightforward,” O’Connor says. “We should approach these unusual traces from as many different angles as we can.”

For her team, that might mean digging further into the mysteries of Enantiornithes feeding habits. While one specimen in Spain yielded traces of freshwater invertebrates, the Jehol Biota fossils have been less forthcoming. “The bottom line is, it’s really weird that we don’t have any evidence of diet for this group,” O’Connor says. “It just seems improbable that this entire diverse clade was eating soft things that don’t preserve traces.”

That’s on top of the fact that the other aspects of the fossils are so well-preserved. “They’re just amazing, with all their feathers and sometimes even more, like all the tissue of the body,” O’Connor says. “They look like roadkill. It’s really incredible.”

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Dinosaur fossils can be, for lack of a better term, rather bare-bones—particularly in their delicate, easily-destroyed nether regions, which can fall prey to the ravages of scavengers, or an explosive release of postmortem gas. But after working with a dinosaur specimen from the Senckenberg Natural History Museum in Germany, Jakob Vinther, a paleontologist at the University of Bristol, returned and realized that its private parts were unusually well-preserved.

“I was thinking, I wonder if anybody has ever found a dinosaur cloaca before?” he recalls.

A cloaca, for those who aren’t familiar, is an opening common to non-mammalian (and a few mammalian) vertebrates that operates as a sort of one-size-fits-all funnel for sex, pooping, urination, and reproduction. In a study published yesterday in the journal Current Biology, Vinther and his colleagues, paleoartist Robert Nicholls and University of Massachusetts Amherst biologist Diane A. Kelly, were able to three-dimensionally reconstruct and describe what Vinther says is the only non-avian dinosaur cloaca known to be preserved.

Though it’s been described this way, a cloaca is “more than just a butthole,” says Vinther. “It’s the Swiss army knife of back ends.” For help with their description, Vinther says, the study authors looked to the wide-ranging cloaca of other land-dwelling vertebrates. Some, such as those belonging to turtles, look like a wizened, puckered grin. The cloaca of birds, our present-day dinosaurs, look “kind of like a cyst that needs to be popped,” Vintehr explains, while the cloaca of crocodile are covered in distinct scales, forming a sort of raised lobe with a slit in the middle.

The dinosaur owner of this particular cloaca is an approximately 120 million-year-old Psittacosaurus, hailing from what is now the Liaoning province in northeastern China. About the size of a labrador, the Psittacosaurus was surprisingly cute for a dinosaur, Vinther says, with scaly skin and horns on either side of its flat, E.T.-like face. The dinosaur’s cloaca appears to have a distinct color, which could have been used to signal for mates, as is sometimes the case for birds. It has a set of lips that join in a v-shape around a bean-like dorsal lobe, and contains what appears to be a coprolite, also known as fossilized poop (though the animal did not necessarily experience a dramatic mid-bowel-movement death, Vinther says; it could have emerged afterwards).

There are some similarities to the crocodile cloaca, co-author Diane Kelly—an expert in the evolution of copulatory systems—told the New York Times, and the study suggests that, like the crocodile, this dinosaur cloaca may have housed glands responsible for spewing out mate-attracting scents.

“The shape and color of the tissue that’s preserved suggests that these animals might have used both odor and visual signals to interact with other members of their species,” Kelly said in an email.

We’re only talking about one set of fossilized dinosaur privates, which limits the scope of any mate signalling takeaways, the study explains. But, though Vinther notes that these revelations aren’t “going to cure cancer, or prevent totalitarian people from entering political systems,” they do add a little piece to the puzzle of what life used to look like, which helps us understand why the living world looks the way it does today.

“Perhaps,” Vinther says, “there was a glorious past where dinosaurs were strutting around and showing their cloacas off.” One can only hope.

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Dinosaurs haven’t roamed the Earth for quite some time, but we find out new things about them all the time. In fact, we’re now ready to reveal the first full dinosaur skeleton ever found!

Below, some dinosaur gifts for kids, dogs, botanists, and just your regular run-of-the-mill nerds.

Unforgettable dinosaur gifts for kids and adults alike

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Let your kid practice for a future paleontology career with this 12-dinosaur excavation kit. Soak the clay eggs in water and carefully chip away to reveal mini dinosaurs. Use the excavation guide to identify the species and learn about your new favorite dinosaurs.

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Plant a treat for a stegosaurus. You can even plant one in a stegosaurus. Have a prehistory-themed garden on your desk or in your kitchen. Choose between 3 dinosaurs planters and a variety of colors.

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Check out this 3D-printed Tyrannosaurus skull shower head. The plastic head comes in a variety of colors and will fit on any ½-inch pipe.

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Each of these glycerin-based colored soaps comes with a dinosaur toy inside. Being clean is more fun when there are dinosaur toys involved.

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Kids love pop-up books. So do I. Think of the Encyclopedia Prehistorica Dinosaurs: The Definitive Pop-Up as an in-your-face, immersive educational dinosaur experience.

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Is your little pup as ferocious as a raptor? Even if they aren’t, this black polar fleece dog costume will make them look like they are. Available in all sizes and multiple colors.

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This adorable dinosaur-shaped marker holder is made of smooth, Michigan hardwood and has a walnut oil coating.

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Teach your kids about dinosaurs with this kid’s book packed with dino-facts. Learn about their habits, the origins of their names, and (thanks to large illustrations) the make-up of their bodies. It really is The Most Complete Dinosaur Reference Ever.

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This Baltic birch dinosaur wine holder holds a standard 750ml wine bottle can be made with a dark walnut finish, a beeswax and orange oil finish, or an unfinished natural wood.

More gift ideas for the science-inclined

Still haven’t found something for everyone on your list? Check out these unique science gifts for kids, or these out-of-this-world space gifts.

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Gatherings have been upended this year, as many of us meet over Zoom or in distanced and masked settings outdoors to avoid the risk of contributing to the spread of COVID-19. But one thing hasn’t changed: Humans are social animals, and we need each other. New research that analyzed the fossil record of Egg Mountain, a paleontology site in Montana, suggests that this gregarious trait may go farther back than scientists previously thought.

Published in Nature Ecology & Evolution this week, the work investigates a newly identified small mammal from the Late Cretaceous epoch (about 75.5 million years ago) that resembles today’s rodent. The researchers named the animal Filikomys primaevus (“youthful, friendly mouse”) because they believe the palm-sized creature lived in groups. The fossilized remains have been found in a number of sites on the mountain, and all of them were found in close proximity to others of the same species.

“They occur in these clusters of either two to five individuals with near-complete skeletons and skulls,” says study author Lucas N. Weaver, a Ph.D candidate in the University of Washington’s department of biology. This placement, along with the fact that multiple individuals of different ages and genders make up these clusters, suggests to Weaver and his colleagues that the animals likely lived together.

They also believe that the animals lived in burrows, much as modern chipmunks do, based on the fact that the skeletons, which were well-preserved, appear to have a strong front end—a feature known to be good for digging.

If true, this would be the earliest example of mammals exhibiting social behavior beyond coming together to mate or raise young. The majority of modern mammals—about 70 percent—aren’t social creatures, Weaver says, and the trait was previously believed to have evolved at the same time as the placental group of mammals, which includes humans and other apes.

Scientists used to believe that the mammals that lived prior to the KT extinction event, which wiped out the dinosaurs, were relatively unsophisticated creatures. In this framing, it took the dinos’ extinction to open up new spaces for mammals to evolve into. But studies in recent years have shown that might not be the case, Weaver says, and this paper is a contribution to that idea. “It’s adding to this growing narrative that Mesozoic mammals were actually very diverse,” he says.

Given the evidence, “The logical inference is that there is some overlapping intergenerational gathering of these animals,” says Jennifer E. Smith, a Mills College professor of biology who studies sociality in mammals. However, she cautions, without a time machine it’s impossible to know for sure what the social lives of the friendly mice of Egg Mountain actually looked like. The fossil record can only say so much about how animals behaved when they were alive.

Still, “I think it’s a great building block for future studies to learn more broadly about mammalian social evolution,” she says.

Smith is particularly intrigued by the fact that these animals all seem to have died together or been placed together in the burrows after death. We know that mammals like humans, elephants, and even honeybees have ritualized ways of disposing of their dead, and that might be what’s happening with these fossils, she says.

This research is the newest finding out of the Egg Mountain site, which contains a wealth of information about the animals of the Cretaceous. But Weaver says more papers are on the way. Personally, he’s working on research to better understand the physiology of the multituberculates, the large and diverse group of mammals to which the friendly mice belong. He also anticipates more work on the evolution of the multituberculates. “Now that we have these skulls and complete dentition and skeletons, we can ask much more detailed questions about their evolutionary relationships.”

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About 160 million years ago, two tiny dinosaurs known as Yi qi and Ambopteryx longibrachium glided through the trees in present-day China. Unfortunately for Yi and Ambopteryx, these aerial abilities were pretty underwhelming, scientists reported on October 22 in the journal iScience. The researchers examined soft tissues preserved in a fossil specimen of Yi and used mathematical models to simulate how both dinosaurs would have glided. They found that the bat-like dinosaurs would have been clumsy gliders and probably went extinct because they couldn’t compete with the keen flying abilities of birds and early mammalian gliders.

“They had basically just gotten started and then a better model came in and they got pushed out,” says T. Alexander Dececchi, a paleontologist at Mount Marty University in Yankton, South Dakota and a coauthor of the new findings. “They didn’t get a chance to better themselves so they could put up a good fight.”

Yi and Ambopteryx were probably about the size of a large pigeon or small crow. Their bodies were covered in downy, fluffy feathers and their wings were built with batlike membranes of skin. To understand the little creatures’ gliding capabilities, Dececchi’s team scanned a fossilized Yi specimen using a technique called laser-stimulated fluorescence. This allowed the researchers to capture detailed information about their claws and wings.

Dececchi and his team then reconstructed what shape the dinosaurs’ wings might have been and compared this configuration to those of other flying animals like birds and bats. Using mathematical models, the researchers estimated how Yi and Ambopteryx might have flown or glided at different weights and wing sizes.

It turned out that Yi and Ambopteryx couldn’t have taken off from the ground or flapped their wings very easily like most birds and bats can. The dinosaurs could glide between gaps in the canopy, but their wings wouldn’t have been very maneuverable. They also were carrying more bulk relative to their wing area than present-day gliders like flying squirrels, which meant the dinosaurs would need to glide faster to generate enough lift to keep themselves aloft.

This need for speed would have posed a few problems. “It makes it harder to turn, it makes it harder to do fine-scale adjustments…it’s harder to pinpoint where you’re going to land,” Dececchi says. “If you’re going to be flying fast into a tree, it increases the chance you’re going to hurt yourself when you crash.”

All in all, these dinosaurs had very inefficient wings, he says. They likely couldn’t outfly aerial predators such as pterosaurs, which were a much more accomplished group of flying reptiles. What’s more, their legs weren’t really built for running. On the ground, the dinosaurs would’ve been slow and awkward and easily picked off by predators.

When Yi and Ambopteryx first appeared in the late Jurassic Period, they could feast on seeds, insects, and small nuts without much competition. Within a few million years, however, Archaeopteryx and other early birds evolved. Archaeopteryx couldn’t match the aerial acrobatics of today’s birds, but they probably could launch themselves off the ground and fly in short bursts. “Suddenly the gliders have competition from something that was going for the exact same resources they were but was better at getting around,” Dececchi says.

Yi and Ambopteryx likely went extinct before they had the opportunity to improve their flying abilities or develop adaptations like those seen in today’s gliders; flying squirrels and sugar gliders are nocturnal, which allows them to feed separately from most birds, who would beat them in a flying competition.

There are only a few known fossils of Yi and the recently-discovered Ambopteryx. It’s possible that scientists will eventually discover more recent remains. “Future work may find one of these guys who did escape into that nocturnal realm for a little while,” Dececchi says. Even as a “failed experiment,” though, these gliders can help scientists understand the origins of flight, Dececchi and his colleagues concluded.

“What changes are the critical ones to get into the air?” he says. “They help inform me [about] how the actual line that led to birds evolved because I can see what went wrong when dinosaurs tried this path to get into the air.”

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Breakthrough is a short film anthology and educational outreach program from the Science Friday Initiative and Howard Hughes Medical Institute (HHMI) Tangled Bank Studios. This short documentary series follows women working at the forefront of their scientific field, blending deeply personal stories with innovative research and discoveries. Watch the latest season of the film series at BreakthroughFilms.org.

When paleontologist Jingmai O’Connor looks at the abdomen of a small, ancient avian fossil, she gets a thrill when she spots a jumble of nodules, no bigger than a scattering of goosebumps, protruding from the creature’s bones. Their presence could mean the animal’s metabolism supported rapid egg growth. In another specimen, O’Connor discovers an entire bird gobbled up inside of a chicken-sized feathered dinosaur, revealing a clue about the ecology in which both animals lived.

O’Connor’s obsessive eye for detail and encyclopedic knowledge of morphology comes in handy when she’s placing these fossils on the ancient family tree of birds. She credits those skills, as well as her enthusiasm for science, to her mother, a geochemist who earned her PhD while raising O’Connor and her three siblings. It was also her mother’s influence that led O’Connor to focus on geology—and to explore her own Chinese-American roots—by focusing her studies on the scores of bird fossils coming out of China at the turn of the century.

Dozens of discoveries later, O’Connor is now a professor at the Institute of Vertebrate Paleontology in Beijing where she uses the world’s largest collection of avian dinosaurs to explore the changes in ancient species that led to wings, tail feathers, flight, and many other adaptations seen in modern birds.

Check out the full episode here:

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About 66 million years ago, an asteroid 7.5 miles (12 kilometers) in diameter slammed into the Yucatán Peninsula of present-day Mexico. The impact vaporized rock, ignited wildfires, and created a cloud of soot and dust that darkened and cooled the entire planet. These inhospitable conditions led to the extinction of 76 percent of Earth’s species, including the dinosaurs.

Now scientists have investigated how much of this soot came from the wildfires, and how much came from older materials like coal and oil in rocks from the cavity, known as the Chicxulub impact crater. The chemical composition of sediments from the crater and two distant deep-sea sites suggests that the initial wave of carbon came from rapidly-heated fossil sources, the team reported September 28 in the journal Proceedings of the National Academy of Sciences. Soot from wildfires later exacerbated and perhaps lengthened the “impact winter” that Earth endured, the team concluded.

“There were multiple processes going on that impacted the extinction,” says Shelby Lyons, a geologist at Pennsylvania State University and coauthor of the new study. What this paper shows, she says, is that carbon from the rocks contributed as well.

For decades, researchers have been finding burned carbon compounds buried within sediments from around the world dating to the period when the dinosaurs were wiped out. These included charcoal, soot, and chemicals called polycyclic aromatic hydrocarbons (PAHs).

“These compounds are formed typically when things are being heated,” Lyons says. “You could find them when you are grilling meats, you could find them out of the exhaust of a car, you could find them from smoke from the wildfires in California, you could find them in charcoal that’s left behind.”

Debate remains about the intensity of the pulse of heat from the impact and resulting wildfires, says Clay Tabor, a paleoclimatologist at the University of Connecticut who was not involved in the research. This raises questions about the relative importance of the fires—which burned plant matter, destroyed habitats, and sent smoke billowing into the atmosphere—and fossil fuels formed from decayed plants and animals over millions of years. “Either way, soot seems to play an important role in the extinction,” Tabor said in an email. “This paper is an important step towards understanding the sources of burn markers.”

To probe the origin of these materials, Lyons and her colleagues examined samples from the crater and two sites in the South Atlantic and Indian Oceans. They focused on PAHs—compounds assembled from carbon atoms fused together into rings that slightly resemble chicken wire. PAHs are created when carbon is heated, whether that happens slowly in Earth’s crust or within seconds during a fire.

Most of the PAHs that Lyons and her team observed had a distinctive shape. “The material had properties that looked like it was…burned extremely rapidly, but the initial source of it was from ancient carbon,” Lyons says. PAHs created when wildfires swept over the landscape would have had a different chemical structure, she says.

Lyons and her team estimate that between 7.5 × 1014 and 2.5 × 1015 grams (about the weight of 7550 Empire State Buildings) of this ancient carbon was blasted into the sky and circulated around the globe within a matter of hours. This soot, along with massive amounts of dust and sulfur-containing compounds from the vaporized rock, would have blocked out sunlight and initiated the cold, dark impact winter. “It would have settled in the upper atmosphere and it would have remained there for years,” Lyons says.

However, there was also plenty of charcoal buried in the sediments, which forms when woody matter is burned. Lyons and her colleagues argue, though, that most of the soot from these fires would have remained lower in the atmosphere and been removed by precipitation. And the soot that did reach the upper atmosphere would have taken a while to accumulate.

“Burned material from the target rock gets put into Earth’s upper atmosphere within hours, whereas for wildfires it can take months,” Lyons says. “A small portion of the burned material comes from the target rock, but that material may have been the most impactful.”

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In the past half billion years of Earth’s history, there have been five widely-accepted major mass extinctions, but new findings published recently in Science Advances suggest that there may have been another—one that created conditions that allowed dinosaurs to take over the world.

The newly proposed mass extinction, which occurred during a period of time 233 million years ago called the Carnian Pluvial Episode (CPE), resulted in the loss of 33 percent of marine genera (the next-highest level of taxonomy above species) according to the study. Large volcanic eruptions in western Canada likely caused the event by emitting large amounts of greenhouse gases, causing rapid global warming and a period of increased rainfall that lasted roughly one million years. Afterward, climate conditions rapidly changed from rainy to arid, which, coupled with the increased plant growth during the period, provided a warm, oxygen-rich environment ideal for dinosaurs to flourish.

It’s tricky to gather enough data to define a new mass extinction as “major.” This happens when 75 percent of species in the world die out within a relatively short period of time (geologically speaking, which could mean several thousands of years), but it’s hard to know exactly what fraction of flora and fauna died off in any given period. In the last 545 million years, there have been at least five of these events, most of them caused by large volcanic eruptions. There have been many minor mass extinctions throughout the history of the Earth, as well, where roughly 20 to 40 percent of species disappear.

According to Dr. Michael Rampino, a geologist at New York University who published a paper last year about a different potential major mass extinction 260 million years ago, the CPE event does not quite meet the criteria for such a calamitous event. The 33 percent of marine genera that vanished during the period, though significant, do not measure up to the roughly 75 to 90 percent of species (generally around 45 percent of genera, though there’s no direct conversion) that would need to die off for an event like this to be considered “major.”

Rampino says the loss due to the CPE event was “not a total disaster, like the Cretaceous-Tertiary boundary,” in which all non-avian dinosaurs died out, “but enough where paleontologists looking back at the records can see that a relatively large number of the species that were there disappeared.”

It may be hasty to completely rule out the CPE as a major mass extinction, though. The researchers acknowledged in their article that they do not have precise enough dating to verify how many species, especially land animals and plants, actually died out in the time frame that the researchers investigated. There might have been more that disappeared during this time—it will take more precise dating mechanisms to know for sure.

But just because the CPE extinction was not as major as the five largest does not mean it was insignificant. Mass die-offs can wipe out species that flourished in the prior environment, leaving space for other groups to evolve and spread in the post-catastrophe world.

“It’s a way of resetting evolution, or resetting the major players in the various ecosystems that were affected by the extinction,” says Rampino.

Regardless of whether this event joins the ranks of the five widely-accepted major mass extinctions in the future, it certainly set the stage for the diversification of species that led to the creation of modern ecosystems—in particular, the evolution of the first mammals and more modern forms of coral, plankton and reptiles.

“You sort of look at it as if you’re growing a bush, and you trim it back, and it starts to grow back again,” says Rampino. “But maybe some of the branches that weren’t growing so well before start to grow better, and some of the branches are gone.” The volcanic eruption and sudden climate change spelled disaster for many species—but in the end, it allowed many more to thrive.

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Cancer follows a fairly standard protocol: Cells multiply out of control until they take over key organs necessary for survival. Creatures across the animal kingdom from humans to birds to reptiles can all get cancer, and, as researchers report this week, so can dinosaurs that roamed the Earth millions of years ago. Knowing more about how and why the mysterious forms in these ancient creatures could help doctors prevent more animals from meeting the same fate.

Scientists from the Royal Ontario Museum and McMaster University have discovered that an ancient triceratops-like beast that lived over 75 million years ago developed an osteosarcoma tumor in its leg bone. They published their new findings in The Lancet last week.

The team of scientists, including health experts and paleontologists, had been searching for human-like diseases in ancient dinos by digging through old fossils at Canada’s Royal Tyrrell Museum and stumbled upon the fibula of a Centrosaurus apertus that had scientists had uncovered in Alberta thirty years ago.

Paleontologists at the time had diagnosed the malformed fossil as an oddly healed fracture. But a new team of researchers took a closer look, examining and running tests as they would if the bone belonged to a human patient. That meant coming up with a list of possible diagnoses, and eventually, biopsying slices of the bone under a microscope to take a closer peek.

“We had to do something called destructive analysis which is exactly what it sounds like,” says Seper Ehktari, an author of the study and orthopedic surgery resident at McMaster University.

With this closer examination, Ehktari and his team realized the destruction of the bone was caused by osteosarcoma which still impacts some 800 to 900 new human patients in the US yearly. Ehktari adds that it’s not only humans that get this disease, but other mammals and creatures more closely related to dinosaurs like chickens and cockatoos.

Jennifer Anne, a paleontologist at the Children’s Museum of Indiana not involved in the study, notes that this is not the first spotting of cancer in dinosaurs. There’s been a handful of known cases (a duck-billed dino has also had signs of bone cancer). However, it does open up a whole new group of dinosaurs to novel discoveries regarding cancer that we might’ve missed before.

“We are also gaining a lot more knowledge about cancer in non-human animals,” Anne says. “That information coupled with better access to new technology like CT scanners that can scan dense fossils means paleontologists are going to get better at identifying and, to the best of their ability, diagnosing paleopathologies.”

Beyond just satisfying our curiosity for the lives of the massive dinosaurs that once roamed our current-day backyards, discovering more about cancers in their ancient forms could help us diagnose and fight them in today’s creatures, including in us humans. Osteosarcomas in humans typically develop when people are growing at a super-fast rate, typically around age 10 to 20, says Ehktari.

Seeing as dinosaurs also grow rapidly from tiny babies to massive beasts is another reinforcement to the theory that rapid growth might have something to do with the rapid reproduction of cells, Ehktari says. After all, he adds, the more cells are growing and reproducing, the more likely it is that a handful of them could “go rogue.”

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About 237 million years ago, a tiny, bug-eating reptile hopped along the sandy riverbanks of present-day Madagascar. Standing about 4 inches tall at the hip, this little creature lived just a few million years before the advent of dinosaurs and pterosaurs—the largest animals ever to walk the land or take to the skies. Its petite stature suggests that dinosaurs and pterosaurs may also have had very humble beginnings.

“Their early history is very mysterious because there are very few fossils,” says Christian Kammerer, a paleontologist at the North Carolina Museum of Natural Sciences in Raleigh, who reported the ancient reptile’s discovery on July 6 in Proceedings of the National Academy of Sciences. “Looking at body size evolution in the group, we find good evidence that the common ancestor of dinosaurs and pterosaurs…would have [had a] very small body size.”

Kammerer and his colleagues named the little reptile Kongonaphon kely, which is derived from Malagasy and ancient Greek words that mean “tiny bug slayer.” Kongonaphon belonged to a group called Ornithodira, which also includes dinosaurs, pterosaurs, and their descendants. 

Among the pieces of the partial skeleton that Kammerer’s team identified were an upper jawbone and bones from the arm, leg, foot, and tail. Kongonaphon’s teeth are small and cone-shaped and lack the serrations seen in the steak knife-shaped teeth that belonged to larger predators. Instead, they resemble the teeth that you’d find today in small, insect-eating lizards.

“By looking at wear on teeth you can tell what fossil animals were eating, and that also matches up with an insectivorous diet,” Kammerer says. “We expect this was a small, very light-bodied predator of invertebrates, mostly insects, [that was] probably running around—maybe hopping around—in its environment.”

The researchers also examined fine slices of Kongonaphon’s shinbone under the microscope. Like trees, dinosaur bones contain growth rings that can be used to estimate age. Kammerer’s team determined that the Kongonaphon was at least two years old when it died and was no longer growing rapidly, suggesting that it had reached maturity.

The Kongonaphon’s right thighbone was missing one tip but probably measured about 1.57 inches in length. Thighbones are one of the main sources of support for the skeleton, which means they can be used to gauge an animal’s total body size. It’s possible that pocket sized ornithodirans like Kongonaphon were common during the Triassic Period, but their tiny bones were rarely preserved as fossils. “Larger bones are less likely to be totally destroyed by scavengers or torn apart by the elements before they get buried,” Kammerer says.

Kammerer and his colleagues also examined how body size may have evolved over time in ornithodirans and other reptiles. While Kongonaphon was probably not a direct ancestor of dinosaurs, its small size is part of a larger trend that indicates that ornithodirans became smaller shortly before dinosaurs and pterosaurs emerged. Their small size and insectivorous diet may have allowed them to avoid competing with the ancestors of mammals and much larger reptiles, which dined on plants and larger animals.

Becoming smaller may have also prepared ornithodirans for the evolution of flight. “All of the flying or even gliding animals start out fairly small,” Kammerer says. It’s even possible that downsizing was related to the emergence of feathers and similar fuzzy coverings, he adds. Small animals lose heat quickly, and these fuzzy coverings may have first evolved to insulate early ornithodirans such as Kongonaphon.

“Some sort of shaggy covering becomes a necessary way to survive while also being able to take advantage of the ecological benefits of being a small animal,” Kammerer says.

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