Tag Archives: dinosaurs

Fossil Friday: Italy’s largest discovery of dinosaurs is a herd of 11 specimens

Every once in a while, paleontologists make some breathtaking discoveries. Recently, it was the turn of Italian paleontologists to do so, and a new paper reports on the remarkable finding: a herd of 11 fossilized dinosaurs, including the largest and most complete such reptile to ever be discovered in the country.

The fossilized skeleton of ‘Bruno’. Image credits Alfio A. Chiarenza et al., (2021), Nature Scientific Reports.

Italy isn’t known as a hotbed of dinosaur fossils. There have been a handful of discoveries here, most of them in the last 30 years or so. By and large, however, Italian dinosaur hunters generally look to places outside of their motherland when searching for fossils.

But a new paper comes to show that there are still hidden paleontological gems to be found in Italy. The fossilized herd was unearthed at the Villaggio del Pescatore site, a protected area in Italy that has yielded dinosaur fossils in the past, as well.

An impressive haul

“Italy is not known for dinosaurs and, although we had a few lucky strikes in the past, now we have a whole herd at one dinosaur site,” said Federico Fanti, a professor at the University of Bologna and corresponding author of the paper describing the findings.

Villaggio del Pescatore is the site of a former limestone quarry close to the city of Trieste. Back in 1996, an almost complete dinosaur skeleton was unearthed here, initially believed to have belonged to a “dwarf species”, which paleontologists named “Antonio” at the time. However, the new discovery calls into question the assumption that it belonged to a dwarf species.

The freshly-discovered herd consists of 11 specimens of hadrosaurids of the species Tethyshadros insularis. These dinosaurs lived some 80 million years ago and could reach up to five meters (around 16 feet) in length. The herd includes the largest and most complete dinosaur skeleton ever recovered from Italy, an individual christened “Bruno”. Beyond how spectacular the find itself is, it also helped paleontologists better identify the species of Antonio.

Unlike previously believed, Antonio was not a dwarf dinosaur, but rather a juvenile — most likely a member of the same herd unearthed now.

Geology and geographic context of Villaggio del Pescatore (VdP). The star symbol marks the relative position in the paleogeography of the Tethys (c) where VdP most likely originated. Image credits Alfio A. Chiarenza et al., (2021), Nature Scientific Reports.

“Bruno is the biggest and oldest of the group, and the most complete dinosaur skeleton ever found in Italy,” said Fanti.

“We knew there were dinosaurs at the site after the discovery of Antonio, but up until now nobody actually checked to see how many. What we have now are multiple bones belonging to the same herd.”

Around the time these dinosaurs were alive, the site at Villaggio del Pescatore was very close to water, being on the shoreline of the ancient layout of the Mediterranean sea. The discovery of fish, crocodiles, flying reptiles, and small shrimp alongside the dinosaur herd provides further evidence of this.

“This is super cool as we can figure out the kind of environment the dinosaurs lived and died in,” added Fanti. “During that period, the area was very close to the shoreline in a tropical, warm and humid environment capable of feeding herds of dinosaurs.”

The site is still closed to the public, but paleontologists hope to make at least part of it open to visitation in the future. Until then, fossil aficionados can see some of the fossils recovered so far at the site at the Civic Museum of Natural History in Trieste.

The paper “An Italian dinosaur Lagerstätte reveals the tempo and mode of hadrosauriform body size evolution” has been published in the journal Nature Scientific Reports.

Why did birds survive the asteroid impact that wiped out the dinosaurs?

The actual fossil (top) and the digital brain reconstruction of Ichthyornis, an ancient bird that lived during the Cretaceous. Credit: Torres et al, Science Advances.

You might have heard that birds are essentially living dinosaurs, just like humans are mammals. Dinosaurs actually represented a huge group spanning countless species of reptiles that held the top carnivore and top herbivore spots. But out of all these different dinosaur groups, it was only birds that survived the disastrous asteroid impact from 65 million years ago, which killed 80% of all life on Earth.

A new study tried to demystify what helped birds to survive when all other dinosaurs failed. According to the findings reported in the journal Science Advances, many ancient species of birds also perished in the wake of the damning asteroid impact off the coast of Mexico’s Yucatan Peninsula. However, the scientists found that the lineages of birds that did endure must have had larger forebrains. Turns out, you want to pick brains over brawn during an apocalypse.

Who you calling bird brain

The fossil record hasn’t been kind to bird bones, which are more often than not too delicate and fragile to endure over millions of years. What few bird fossils paleontologists know about though are enough to firmly place birds in the same group as dinosaurs, having evolved from a group of meat-eating dinosaurs known as theropods. It’s the same group that the famous Tyrannosaurus rex belonged to, although birds evolved from much smaller theropods.

After a long reign spanning more than 140 million years, the age of the dinosaurs came to an abrupt end. Only puny birds remained, which rapidly expanded and filled vacant ecological roles. Some 150 million years ago, the oldest birds looked like feathered dinosaurs and had sharp teeth. Over time birds lost their teeth and evolved beaks.

Not very much is known though about the brains of early birds since their braincases (the interior of the skull) rarely fossilized. This is why scientists are very excited by a partial skull belonging to Ichthyornis, an ancient bird that lived about 85 million years ago in Kansas.

In a new study, researchers at the University of Texas at Austin have completed an X-ray CT scan of the fossil, digitally reconstructing the Cretaceous bird’s facial skeleton and braincase in 3D without having to invasively alter the fossils in any way.

The analysis showed that Ichthyornis‘ brain was surprisingly similar to that of other dinosaurs, in contrast to living birds that have disproportionately large forebrains relative to the rest of their brain regions. However, the ancient bird’s brain did have an ace up its sleeve: a wulst. This brain structure was previously observed only in bird species that appeared after the mass extinction event caused by the asteroid impact. The wulst is thought to have played a major role in visual and sensory processing that could have played a critical role in flight.

Ancient birds had brains more closely resembling those of dinosaurs rather than the birds of modern birds. The ancestors of modern birds likely later developed a larger cerebrum, helping them survive the mass extinction. Credit: Science Advances.

Finding a wulst in the brain of a Cretaceous dinosaur shows that ancient birds had brains that were more complex than previously thought. And since Ichthyornis is very closely related to modern birds but still lacked the massive forebrain we’re used to seeing in living birds, the researchers inferred that “those big brains evolved in the ancestor of living birds,” Chris Torres, a National Science Foundation postdoctoral research fellow in the Heritage College of Osteopathic Medicine at Ohio University, told Live Science. Torres was a graduate student at the University of Texas when he participated in the fossils’ CT scanning.

Ichthyornis exhibited a wulst and segmented palate, previously proposed to have arisen within extant birds. The origin of Aves (extant birds) is marked by larger, reshaped brains indicating selection for relatively large telencephala and eyes but not by uniquely small body size. Sensory system differences, potentially linked to these shifts, may help explain avian survivorship relative to other dinosaurs,” the authors wrote in their study.

The combination of bigger brains, small size, their ability to eat a wider palate of foods, and their ability to fly ultimately may have helped birds survive the last mass extinction. Today, there are at least 11,000 bird species. 

“Hobbit” creature shows life evolved quickly after dinosaur extinction

The epic adventures of Bilbo Baggins act as a prequel to J.R.R. Tolkien’s Lord of The Rings trilogy. Bilbo encounters many creatures and races, including an enormous, shape-shifting warrior named Beorn.

“He is very strong, and he is a skin-changer,” the wizard Gandalf says of him, noting that “Sometimes he is a huge black bear, sometimes he is a great strong black-haired man with huge arms and a great beard.”

Researchers have now immortalized Beorn with the discovery of an extinct mammal that rose to prominence 65 million years ago, shortly after the demise of the dinosaurs. They call this creature Beornus honeyi.

Left to right, Conacodon hettingeri, Miniconus jeanninae, Beornus honeyi. Credit: Banana Art Studio

The creature is part of a group of three newly discovered species: Miniconus jeanninae, Conacodon hettingeri, and Beornus honeyi. They differ in size, with the Beorn-named creature being about as big as a cat — much larger than the mostly mouse-to-rat-sized mammals that inhabited North America after the fall of the dinosaurs.

So although the creature wasn’t necessarily large by today’s standards, it was relatively big for its day. In fact, the difference between the three creatures is so significant that the researchers now believe mammal evolution after the dinosaurs occurred much quicker than previously expected.

All three creatures are part of the group of mammals called archaic ungulates (or condylarths) — ancestors of today’s hoofed mammals (horses, elephants, cows, hippos, etc.). Specifically, they belong to a family called Periptychidae, which is known for its teeth.

This family of animals has swollen premolars and unusual vertical enamel ridges on their teeth, which may be linked to an omnivorous diet (but also don’t rule out a herbivore diet). Due to these teeth, researchers also believe that the creatures had puffy cheeks — hence the Hobbit name: when Beorn transformed into a bear, he had similarly puffed cheeks.

Beornus was probably just one of the many mammals that filled in the environmental niches left open by the dinosaurs.

“When the dinosaurs went extinct, access to different foods and environments enabled mammals to flourish and diversify rapidly in their tooth anatomy and evolve larger body size,” says lead author Madelaine Atteberry from the University of Colorado Geological Sciences Department. “They clearly took advantage of this opportunity, as we can see from the radiation of new mammal species that took place in a relatively short amount of time following the mass extinction.”

Previous studies suggested that condylarths and their relatives were diversifying slowly. However, some recent studies, including this one, suggest more diversity than previously expected. The team used phylogenetic techniques to analyze fossil findings, including the teeth and lower jawbones, from 29 fossil condylarth species in the Great Divide Basin in Wyoming.

Although these analyzed species represent a relatively small part of the entire fauna discovered at the site, it seems unlikely for this to be a coincidence; instead, it’s more likely that the fauna in the area diversified quicker than expected.

“Previous studies suggest that in the first few hundred thousand years after the dinosaur extinction (what is known in North America as the early Puercan) there was relatively low mammal species diversity across the Western Interior of North America, but the discovery of three new species in the Great Divide Basin suggests rapid diversification following the extinction,” says Atteberry. “These new periptychid ‘condylarths’ make up just a small percentage of the more than 420 mammalian fossils uncovered at this site. We haven’t yet fully captured the extent of mammalian diversity in the earliest Paleocene, and predict that several more new species will be described.”

The study “New earliest Paleocene (Puercan) periptychid ‘condylarths’ from the Great Divide Basin, Wyoming, USA” was published in the Journal of Systematic Palaeontology.

Fossil Friday: Australia’s largest known dinosaur identified after a decade of work

A newly-identified titanosaurus, christened Australotitan cooperensis, is one of the 15 largest dino species we’ve ever found. And, so far, it seems to be the largest one ever uncovered in Australia.

Image credits Queensland Museum.

According to estimations from experts, this “southern titan” could likely grow up to 6.5m (21ft) tall and 30m (98.5ft) long, which Google tells me is just a tad longer than a basketball court. Its fossil was discovered on a farm in southwest Queensland almost one decade ago, and paleontologists spent all that time trying to distinguish it from other known species, mostly by comparing scans of it to the bones of known sauropods.

Big-boned down under

The sauropods were a lineage of plant-eating dinosaurs that grew to awesome proportions. Their bulky bodies were fleshed out with very long necks and tails, thin, somewhat stumpy legs, and quite small heads (relative to their overall size). They lived during the Cretaceous period, between 92 to 96 million years ago, and were probably the largest animals to ever walk on dry land.

The new species was christened Cooper (cooperensis means ‘of/from Cooper’ in Latin) for the area where it was unearthed: Cooper Creek. The remote location of this site, as well as the impressive size of the fossils themselves and their condition, made the identification process that much longer. They were unearthed in 2007 on a family farm near Cooper Creek, Eromanga, Australia, on a family farm owned by two of the authors of this paper, Robyn and Stuart Mackenzie.

Artist’s impression of what the dino looked like. Image credits Queensland Museum.

However, enough of the bones were found intact for researchers at the Queensland Museum and the Eromanga Natural History Museum to study and reliably identify.

It is closely related to three known sauropod species: the Wintonotitan, Diamantinasaurus, and Savannasaurus. This would mean that Australia’s largest dinosaur is, appropriately, part of one big family of big animals.

“It’s amazing to think from the first bones discovered by our son, the first digs with the Queensland Museum, through to the development of a not-for-profit museum that runs annual dinosaur digs, all have helped us to get to this point, it’s a real privilege,” Stuart Mackenzie said.

“Australia is one of the last frontiers for dinosaur discovery and Queensland is quickly cementing itself as the palaeo-capital of the nation – there is still plenty more to discover,” said Dr Jim Thompson, chief executive of the Queensland Museum Network.

The paper “A new giant sauropod, Australotitan cooperensis gen. et sp. nov., from the mid-Cretaceous of Australia” has been published in the journal PeerJ.

The dinosaurs may have been wiped out by a comet fragment, not an asteroid

Artist’s reconstruction of Chicxulub Crater soon after impact, 66 million years ago. Image via Detlev Van Ravenswaay/ Science Source.

Around 66 million years ago, a giant asteroid struck our planet off the coast of Mexico. The devastating impact, whose force was equivalent to 10 billion Hiroshima A-bombs, unleashed huge tsunamis hundreds of feet tall, global wildfires, and sent molten rock hurtling all the way to the moon. About 75% of all life on Earth was killed almost instantly, including all non-avian dinosaurs. But according to a controversial Harvard astronomer, the culprit wasn’t an asteroid, but rather a comet fragment from the outer reaches of the solar system.

Since geophysicists first identified the huge impact crater in Chicxulub, Mexico, the site has been the subject of important research probing into the nature of the impactor in order to reconstruct the devastating timeline of the mass extinction that would follow.

We now know, for instance, that the impactor must have been very large, measuring between 10 and 80 kilometers in diameter, judging from the staggering 180-kilometer-wide crater, most of which is submerged in the Pacific Ocean. The impact then shrouded the planet into a decades-long winter, which decimated the suitable environments for dinosaurs.

This leading theory is that this impact arrived from the asteroid belt between Mars and Jupiter, but Harvard’s Professor Avi Loeb and astrophysics graduate student Amir Siraj have published a new study proposing an alternative source.

Loeb is no stranger to controversial theories. Previously, he claimed that the first-ever interstellar object Oumuamua may actually be an alien spaceship. He’s actually being a lot more conservative with his most recent paper published Monday in the journal Scientific Reports.

The pair of researchers performed the statistical analysis and gravitational simulations to essentially reverse-engineer the path the Chicxulub impactor took, showing that the impact actually originated from the Oort cloud — a shell of icy objects that exist in the outermost reaches of the solar system, more than a trillion miles away from Earth.

The Oort cloud is where most of the comets in the solar system are flung from. However, the Chicxulub impact wasn’t produced by a comet, but rather by comet fragments.

According to the researchers’ simulations, many Earth-crossing events were also directly preceded by very close encounters with the Sun. Astronomers call these comets “sun-grazers”.

Due to the gravitational interactions with the Jupiter-Sun system, large comets are torn apart into a large number of smaller fragments. Since the number of fragments large enough to account for the Chicxulub crater was about an order of magnitude greater than the background asteroid or comet population, the researchers simply conclude that it was far more likely that the crater was produced by a comet fragment.

“The solar system acts as a kind of pinball machine,” Siraj said. “Jupiter, the most massive planet, kicks incoming long-period comets into orbits that bring them very close to the sun.”

“And crucially, on the journey back to the Oort cloud, there’s an enhanced probability that one of these fragments hit the Earth,” the scientist added.

The comet fragment hypothesis may explain the unusual composition of the Chicxulub crater, which suggests the impactor was made of carbonaceous chondrite. These minerals are rare amongst main-belt asteroids, but rather widespread among long-period comets that make rounds between the sun and the Oort cloud.

A similar mineral composition was also encountered at the 2-billion-year-old Vredefort crater in South Africa, which is the largest confirmed crater in Earth’s geological history, as well as the Zhamanshin crater in Kazakhstan, which is the largest confirmed crater within the last million years. This is why the researchers plan to use the same approach on these craters as well.

These insights may be important in the future as the new Vera Rubin Observatory in Chile is scheduled to come online next year. The observatory can measure both the composition and tidal disruption of long-period comets, so it should be able to provide data that may confirm the researchers’ model.

“We should see smaller fragments coming to Earth more frequently from the Oort cloud,” Loeb says. “I hope that we can test the theory by having more data on long-period comets, get better statistics, and perhaps see evidence for some fragments.”

Ultimately, these investigations may be crucial in our efforts to mitigate catastrophic cosmic impacts and avoid the same fate as the dinosaurs.

“It must have been an amazing sight, but we don’t want to see that again,” Loeb said.

New research explains why crocodiles are relatively unchanged since dinosaur times

If you look around, you’ll see all sorts of dinosaur descendants, although we call them birds nowadays. But if you want to truly see a dinosaur-like creature, just like it would have roamed the Jurassic age 200 million years ago, just find a crocodile. While some of the species have died out (previous ancestors also consisted of giants as big as the dinosaurs, plant-eaters, fast runners, and serpentine forms that lived in the sea), a lot of what you see now is what you got then.

In new research published in the journal Nature Communications Biology, scientists from University of Bristol explain how crocodiles follow a pattern of evolution known as ‘punctuated equilibrium’.

Crocodiles have many traits which gave them the ability to survive the past 200 million years (Image: Pixabay)

If it ain’t broke, don’t fix it

The rate of crocodile evolution is generally slow, but occasionally they evolve more quickly because the environment has changed and they need to adapt. Specifically, the research suggests that the crocs’ evolution speeds up when the climate is warmer (which it was in the age of the dinosaurs more than it is, today which could explain the different varieties that emerged then), and that their body size increases.

The secret to their slow aging is the limited diversity of crocs and their apparent lack of evolution. It seems the crocodiles arrived at a body plan that was very efficient and versatile enough that they didn’t need to change it in order to survive. They have the ability to thrive in or out of water — they can stay under water for up to an hour — and are able to live in complete darkness. They are also very robust, meaning they can survive horrible injuries.

Believe it or not, it actually isn’t that uncommon for a crocodile to lose a leg and then go on to live another 70 and 100 years.

So while the rest of their dinosaur contemporaries were done in by the asteroid which pancaked itself into the Gulf of Mexico 66 million years ago, crocodiles’ traits — such as the ability to draw energy from the sun, something others couldn’t do — allowed then to continue on life’s journey.

“Our analysis used a machine learning algorithm to estimate rates of evolution,” said lead author Max Stockdale. “Evolutionary rate is the amount of change that has taken place over a given amount of time, which we can work out by comparing measurements from fossils and taking into account how old they are.”

The crocodiles have had a much greater diversity of forms in the past. Examples include fast runners, digging and burrowing forms, herbivores, and ocean-going species. Image credits: University of Bristol.

For the study, the team measured body size — which is important because it interacts with how fast animals grow — how much food the crocodiles needed, the number of their populations, and how likely they were to become extinct.

“It is fascinating to see how intricate a relationship exists between the earth and the living things we share it with,” said Stockdale. “The crocodiles landed upon a lifestyle that was versatile enough to adapt to the enormous environmental changes that have taken place since the dinosaurs were around.”

Now, the next step for the researchers is to see why some crocodiles thrived through the millions of years, while others didn’t.

The study has been published in Nature Communications Biology.

Global warming cleared the way for long-necked giant dinosaurs during the Jurassic

Illustration of Diplodocus. Credit: Pikrepo.

With their long necks, bulging bodies, and long tails, you had to be blind to not notice a sauropod. These were the largest creatures to ever walk on land — some reaching towering heights of 12 meters (40 feet) — but how they managed to grow to such stupendous scale, outcompeting all other herbivores, has always been a matter of great debate among paleontologists. A new study suggests the timeline of sauropod expansion of range and growth in size corresponds with a major extinction triggered by volcanic eruptions in the Early Jurassic.

How some dinosaurs got their long necks

Earth has been no stranger to global cataclysms that wipe out countless species. Over the last half-billion years there have been five major wipeouts, known as mass extinctions, in which well over half of all living creatures disappeared within a geological blink of the eye. Between these major wipeouts, there were minor extinction episodes, such as the Toarcian Oceanic Anoxic Event, during which a series of carbon dioxide-rich volcanic eruptions plunged the world into global warming roughly 182 million years ago.

Similar to human activity today, the Early Jurassic eruptions introduced excess carbon dioxide into the atmosphere, which made the oceans more acidic, thereby causing a mass extinction of marine life. Although plants have a reputation for being a carbon sink, during that time terrestrial ecosystems were dominated by ferns, cycads, and ginkgoes, which didn’t do too well in the now arid, warmer climate. Instead, the shift in climate proved ideal for conifers, which flourished.

However, only animals tall enough to reach the conifers and with stomachs tough enough to digest the spiny leaves could access the nutritional source. One such creature must have been Bagualia alba, a five-ton heavyweight herbivore and the earliest eusauropod, or “true sauropod”, found to date.

B. alba‘s fossils were described by Argentinian paleontologists for the first time in a study published today in the journal Proceedings of the Royal Society B. The fossils, including a partial skull of the ancient giant, were unearthed in the Cañadón Asfalto Basin in Argentina. They suggest B. alba had similar characteristics to famous sauropods like diplodocus and brontosaurus, such as large legs, long necks relative to the body, thick, spoon-shaped teeth, and broad, strong jaws.

During the Early Jurassic, plant-eating sauropods competed with other herbivores, including members of their own clade with less powerful jaws and shorter necks. It has always been unclear why eusauropods grew in leaps and bounds, but now we have a very reasonable explanation — the new fossils show that the Toarcian Oceanic Anoxic Event provided the perfect storm for the dawn of the long-necked sauropods.

According to the authors of the study, this is the first time that the availability of ancient plants have been linked with the evolutionary development of a dinosaur that included them in their diet.

“We show that eusauropod dominance was established after a massive magmatic event impacting southern Gondwana (180–184 Ma) and coincided with severe perturbations to the climate and a drastic decrease in the floral diversity characterized by the rise of conifers with small scaly leaves. Floral and faunal records from other regions suggest these were global changes that impacted the terrestrial ecosystems during the Toarcian warming event and formed part of a second-order mass extinction event,” wrote the researchers from the Museum of Paleontology Egidio Feruglio in Trelew, Argentina.

These legs were made for walking: T. Rex had legs built for marathons, not sprints

Credit: Pickpik.

The consensus among evolutionary biologists is that long legs are indicative of adaptations for higher maximum speed. However, a new study that analyzed the limb mechanics of over 70 species of theropods, including the famous Tyrannosaurus rex, revealed a much more nuanced story.

“When you’re a bigger animal, those adaptations may also be for endurance and efficiency. It may be about being a marathoner rather than a sprinter,” Thomas Holtz, principal lecturer in the University of Maryland’s Department of Geology and co-author of the new study, said in a statement.

Holtz and colleagues measured limb proportions, size ratio, body mass, and gaits for a variety of dinosaurs ranging in size from half a pound to over nine tons.

Paleontologists have often credited T. rex‘s reputation as the top dog of the Cretaceous to its bipedalism and running speed.

Thomas Holtz, principal lecturer in the UMD Department of Geology, measures a dinosaur toe bone. Credit: Thomas Holtz.

Most recently, however, studies investigating the locomotion of the fierce predator haven’t reached very impressive conclusions. In 2017, paleontologist Bill Sellers and his team published a study in which they employed the most comprehensive computer models of their time to simulate how a fleshed-out rex walked and ran.

This model suggests that T. rex could only move at a walking gait of about 12 miles per hour (20 kilometers/hour). Any faster and its foot bones would shatter from the momentum.

Myriam Hirt, a biologist at the German Centre for Integrative Biodiversity Research, employed a different model. Hirt and colleagues analyzed a public database containing information about the top speeds and body sizes of over 500 living species. They used this information to infer T. rex‘s top speed of about 18 miles per hour (29 kilometers/hour) based on its weight.

Among small theropods, long hind limbs gave the advantage of speed, but among the giants, long hind limbs enabled more efficient locomotion. Credit: T. Holtz, University of Maryland.

In both cases, if you ever encountered a T. rex in the luxurious jungle 66 million years ago, you would have actually had a fair chance to make it out alive. There are humans who could have simply outrun the menacing-looking dinosaur.

Although biologists have always known that larger body sizes can limit speed, Holtz and colleagues took things a step further. Their results suggest that longer legs can indeed contribute to higher top speed, but only in small and medium-sized dinosaurs. This wasn’t true for long-legged dinosaurs weighing over 2,200 pounds (one ton), the researchers reported in the journal PLoS ONE.

Among the largest dinosaurs, those with the longest legs needed less energy to move.

“That’s actually a very beneficial savings, because predators tend to spend a great deal of their time foraging, searching for prey,” Holtz said. “If you are burning less fuel during the foraging part of the day, that’s an energy savings that dinosaurs with shorter leg forms didn’t get.”

Paleontologists uncover 66-million-year-old bizarre mammal that shouldn’t exist

 Artist impression of Adalatherium hui. Image credit: Andrey Atuchin / Denver Museum of Nature & Science.

During the Cretaceous, the dinosaurs were in their heyday, whereas mammals were confined to certain ecological niches. Usually, they weren’t bigger than a modern mouse. On the island of Madagascar, however, ancient mammals were allowed to evolve in weird directions. Such is the case of Adalatherium hui, a housecat-sized creature with a mosaic of features, distinct from other mammals that we know of.

The ‘oddest of the odd’

Adalatherium literally means “crazy beast” in Greek, while hui is a nod to Yaoming Hu, a Chinese paleontologist renowned for his work on early mammals who passed away in 2008.

The name is fitting since the ancient mammal “bends and even breaks a lot of rules,” said lead researcher David Krause, curator at the Denver Museum of Nature & Science.

“Knowing what we know about the skeletal anatomy of all living and extinct mammals, it is difficult to imagine that a mammal-like Adalatherium could have evolved,” he added.

The fossils were found preserved in pristine condition in a Mesozoic geological formation in northwestern Madagascar.

Credit: Nature.

Although it may look like a small badger on the outside, Adalatherium had a mix of never-before-seen features. ‘Behind the hood’, paleontologists found that the ancient mammal had more vertebrae in its vertebral column than any of its contemporaries. Its leg bones were strangely curved and its peculiar teeth haven’t been encountered in any other mammal, living or extinct.

“Trying to figure out how it moved is nearly impossible because, for instance, its front end is telling us a different story than its back end,” said Simone Hoffmann of the New York Institute of Technology, a co-author of the study.

What’s more, the 3.1-kg-creature had a nasal cavity unlike any other mammal before it. It had more holes — which served as passageways for nerves and blood vessels — on its face than any known mammal.

Adalatherium belongs to a lesser-known group of mammals known as Gondwanatheria. This rare group of mammals was only known from the ancient supercontinent of Gondwana and previous members were described based on a single skull and isolated jaws and teeth.

The discovery of a complete Gondwanatherian specimen now enables scientists to understand the early evolution of this strange group of extinct mammalian species in the southern hemisphere.

“Gondwanatherians were first thought to be related to modern-day sloths, anteaters, and armadillos but now are known to have been part of a grand evolutionary experiment, doing their own thing, an experiment that failed and was snuffed out in the Eocene, about 45 million years ago,” Krause said.

According to the study published in the journal Nature, the plate tectonics of Gondwana offer hints as to how this bizarre mammal evolved.

Adalatherium hui was found in rocks dated to near the end of the Cretaceous period, at 66 million years ago. Madagascar, with the Indian subcontinent attached to the east, separated from Africa over a hundred million years before and finally became isolated as an island in the Indian Ocean when the Indian subcontinent detached at approximately 88 million years ago and drifted northward,” Dr. Krause said.

“That left the lineage that ultimately resulted in Adalatherium hui to evolve, isolated from mainland populations, for over 20 million years — ample time to develop its many ludicrous features.”


Scientists confirm Spinosaurus was the only swimming dinosaur in history

Credit: Davide Bonadonna, University of Detroit Mercy.

Dinosaurs dominated the terrestrial environment for hundreds of millions of years, but air and water didn’t seem like their strong point at all. However, this shouldn’t be a cause for over-generalization. An international team of scientists has now confirmed that Spinosaurus aegyptiacus could swim, making it the first such dinosaur that we know of.

Spinosaurus is perhaps one of the most bizarre dinosaurs to have ever lived. It had the snout of a crocodile, a relatively large caudal fin on its back, and — as recent fossils have shown — a tadpole-like tail that was about as long as its body.

For decades, reconstructions of the dinosaur’s bulky body suggested that its tail was rather narrow and short. However, tail fossils belonging to Spinosaurus unearthed by paleontologists in Morocco suggest that the tail was larger and exhibited clear adaptations for aquatic environments.

Credit: arco Auditore/Gabriele Bindellini.

In fact, Spinosaurus had such a well-adapted tail that it resembles an oar when viewed from the profile. The end of the tail has no bony bumps, allowing the tip to undulate back and forth such that the dinosaur could propel itself forward through the water of river ecosystems.

“This was basically a dinosaur trying to build a fishtail,” Nizar Ibrahim, the lead researcher examining the fossil, told National Geographic.

Ibrahim had previously suggested that Spinosaurus was semi-aquatic in a 2014 study, but his evidence at the time wasn’t as convincing.

In addition to analyzing the structure and anatomy of the tail itself using photogrammetry, researchers at Harvard University also performed a robotic model of the tail’s movement, further cementing the notion that this dinosaur could swim, as reported in the journal Nature.

“This discovery is the nail in the coffin for the idea that non-avian dinosaurs never invaded the aquatic realm,” Ibrahim said. “This dinosaur was actively pursuing prey in the water column, not just standing in shallow waters waiting for fish to swim by. It probably spent most of its life in the water.”

However, Spinosaurus also spent time on land. How much time the 100-million-year-old dinosaur split between living in the water and in terrestrial environments is not clear at this point.

“These results are consistent with the suite of adaptations for an aquatic lifestyle and piscivorous diet that have previously been documented for Spinosaurus,” the researchers wrote in Nature.

All the bones of Spinosaurus used to describe the dinosaur in the new study are now housed at the University of Casablanca in Morocco. This is somewhat atypical but very welcomed for north-African research, as Moroccan fossils such as these often end up in collections at wealthy universities in Europe or the United States.

Most dinosaurs were warm-blooded, surprising new study claims

The mysteries surrounding dinosaurs have fascinated generations of scholars, with still many open questions regarding the giant creatures that populated the Earth for dozens of millions of years. Now, thanks to a group of Israeli scientists, a key mystery regarding their life may have been solved.

Credit Wikipedia Commons

Ask any kid with an interest in nature, and he’ll tell you that dinosaurs are cold-blooded. But is that really the case?

A team led by professor Hagit Affek of the Institute of Earth Sciences of the Hebrew University of Jerusalem decided to look at whether dinosaurs are indeed cold-blooded — and their suggest that the warm-blooded theory might have a lot more going for it.

The question has far-reaching implications. Hot-blood animals, also known as endothermic, can generate their body heat, which causes them to consume more energy, but equips them better against climatic changes, while cold-blooded animals (exothermic) depend on the sun and require less energy and, therefore, less food.

The team used a new approach to measure historical temperatures, analyzing the chemical bonds between the heavy isotopes of calcium carbonate minerals present in eggshells. This technique allowed scientists to evaluate the temperature of the mother’s body that laid the egg.

Affek and the team worked on fossilized eggs of three species of dinosaurs that lived in high altitudes so to make sure that the body temperatures were the result of an internal process rather than the climate around them. The fossils were selected from Alberta, Canada.

“The global climate during the dinosaur era was significantly warmer than it is today. For this reason, measuring only the body temperatures of dinosaurs who lived near the equator wouldn’t tell us whether they were endo- or exothermic because their body temperature may simply have been a cold-blooded response to the hot climates they lived in,” shared Affek.

After looking at the fossils, the team concluded that the body temperature was between 35° and 40° C, close to the human body temperature (which is between 36,5° and 37,5° C). They verified the findings by applying their same method to mollusk shells that lived in Alberta alongside the dinosaurs.

As part of their evolution, it would seem that at least some dinosaurs went from being lizard-like and cold-blooded to being avian and ward-blooded. According to the researchers, the transformation happened very fast.

“The Mayasaura eggs—a lizard-like dinosaur species that we tested—were already able to self-regulate their body temperature, just like their warm-blooded, bird-like cousins, the Torrdons,” explained Affek.

Until recently it was believed that dinosaurs were cold-blooded in consideration of their close relationship with reptiles. However, in 2014, a study published in the journal Science Studies stated that they represented an intermediate category between the two. The debate has been underway since then and will likely not be quenched by this study alone..

The research has appeared in Science Advances.

A rare and painful tumor that affects humans was found in a 66-million-year-old dinosaur

Hadrosaurs roamed in packs. Credit: Kobayashi Y., et al, Scientific Reports.

Israeli researchers at Tel Aviv University investigated some peculiar cavities in the tail fossils of a hadrosaur, a duck-billed dinosaur that was excavated from Canada’s Dinosaur Provincial Park. Much to their amazement, these cavities were nearly identical to those formed in humans as a result of a rare, cancer-like disease.

Dinosaurs got sick too

The dinosaur fossils were first investigated using high-resolution computer tomography (CT) scans, which enabled the researchers to form a highly accurate image of the hadrosaur’s tail vertebrae without actually disturbing the specimen. When the CT scans were compared to the bones of two humans, known to suffer from a benign tumor called Langerhans cell histiocytosis (LCH), the researchers were amazed by how well the cavities matched.

“The micro-CT produces very high-resolution imaging, up to a few microns,” Dr. Hila May of the Department of Anatomy and Anthropology at Tel Aviv University said in a statement. “We scanned the dinosaur vertebrae and created a computerized 3D reconstruction of the tumor and the blood vessels that fed it. The micro and macro analyses confirmed that it was, in fact, LCH. This is the first time this disease has been identified in a dinosaur.”

LCH causes distinct lesions in the bones and is sometimes described as a rare form of cancer, although this is a somewhat controversial claim since the disease seems to appear and disappear spontaneously. Most of these tumors, which can be extremely painful to live with, appear out of the blue in the bones of children aged 2-10 years. However, most of the cases disappear in time without any intervention.

Hadrosaurs are a kind of duck-billed dinosaur and one of the most common herbivores of the Cretaceous. Their fossils are also among the most common in the record. What’s more, they’re generally so well-preserved that paleontologists have been able to calculate the dinosaurs’ muscle mass, learning that hadrosaurs were very muscular, likely having the ability to outrun predators. There’s even a so-called “Dakota” specimen, which was unearthed in such good condition that it looks more like a mummy than a fossil — researchers were even able to analyze its ligaments, tendons, and what may be internal organs through a CT scan. 

Now, this new study shows that these dinosaurs may have been affected by the same diseases as humans. Previously, other studies found that T. rex suffered from gout and that iguanodons could get osteoarthritis.

Many animals are affected by disease and there’s no reason to believe dinosaurs were any different. However, finding evidence of ancient diseases in dinosaurs is an entirely different matter due to the many challenges involved in identifying telltale signs of in the fossil record.

Photograph of the larger hadrosaur vertebra in lateral view (left) and caudal view (right). The space that contained the overgrowth opens to the caudal surface of the vertebra. Credit: Assaf Ehrenreich, Sackler Faculty of Medicine, Tel Aviv University.

The authors of the new study claim that their new findings will help improve our understanding of paleopathology, a field of science focused on studying disease and infection in the fossil record.

Although extremely rare, signs of disease in dinosaurs could also provide invaluable insights into how diseases evolved alongside animals. Many diseases affecting humans first appear in animals — among them the now-famous Wuhan coronavirus, which likely jumped to humans from snakes.

“These kinds of studies, which are now possible thanks to innovative technology, make an important and interesting contribution to evolutionary medicine, a relatively new field of research that investigates the development and behavior of diseases over time,” notes Prof. Israel Hershkovitz of Tel Aviv University. “We are trying to understand why certain diseases survive evolution with an eye to deciphering what causes them in order to develop new and effective ways of treating them.”

The findings appeared in the journal Scientific Reports.

Fossil footprints show how dinosaurs and early mammals fared during massive eruptions

Fossil footprints from the Karoo Basin of southern Africa could teach us more about how ecosystems respond to truly massive volcanic eruptions.

Palaeoenvironmental reconstruction of the Karoo Basin at the Pliensbachian-Toarcian boundary.
Image credits Bordy et al., (2020), PLoS ONE.

The Karoo Basin is covered in extensive basaltic lava flows from the Early Jurassic. It’s believed that the intense volcanic activity recorded during that time had a powerful impact on global climate and local environments, and it largely coincides with a worldwide extinction event.

The floor is lava

“The fossil footprints were discovered within a thick pile of ancient basaltic lava flows that are ~183 million years old,” explains Emese Bordy of the University of Cape Town, lead author of the paper. “The fossil tracks tell a story from our deep past on how continental ecosystems could co-exist with truly giant volcanic events that can only be studied from the geological record, because they do not have modern equivalents, although they can occur in the future of the Earth.”

The basin was turned into a “land of fire” at the onset of the extinction event, the team explains, yet dinosaurs and synapsids still managed to survive in the hellish landscape. Synapsids are a group of animals that include mammals and their closest fossil relatives. Studying their fossils and the fossils of the tracks they left behind might help up understand how ecosystems respond to powerful stresses.

In this study, Bordy and his team described the footprints of these animals, which were fossilized in a sandstone layer deposited between lava flows around 183 million years ago. They reported on five trackways that total 25 footprints among three types of animals — small synapsids, large bipedal and predatory dinosaurs, and smaller, quadrupedal herbivorous dinosaurs. These were some of the very last animals to inhabit the Karoo Basin before it was flooded with lava.

Since the sandstone layer sits in between the deposited lava, it indicates that the animals survived here even after the onset of volcanic activity which transformed the area into a “land of fire”, according to the authors. Further research is needed to find any undiscovered fossils in this area and more accurately date the local geological formations, they add, so we can better track the ecological shifts that took place before and during the extinction.

The paper “Tracking the Pliensbachian-Toarcian Karoo firewalkers: Trackways of quadruped and biped dinosaurs and mammaliaforms” has been published in the journal PLoS ONE.

‘Dancing dragon’ bridges gap between feathered dinosaurs and birds

Paleontologists have recently described the 120-million-year-old fossils belonging to an ancient extinct species that was a bizarre mix between dinosaurs and birds.

Credit: Erick Toussaint/San Diego Natural History Museum.

The fossils of the newly reported species, dubbed Wulong bohaiensis (“the dancing dragon”), were first unearthed from China more than ten years ago, in the fossil-rich Jiufotang Formation. The region is thought to be one of the first habitats where dinosaurs and early birds co-existed.

The species, which is twice as old as T. rex, has been described based on a fantastically well-preserved specimen, whose feathers look trapped in time.

“The new dinosaur fits in with an incredible radiation of feathered, winged animals that are closely related to the origin of birds,” said postdoctoral researcher Ashley Poust of the San Diego Natural History Museum and UC Berkeley. “Studying specimens like this not only shows us the sometimes surprising paths that ancient life has taken, but also allows us to test ideas about how important bird characteristics, including flight, arose in the distant past.”

According to the new study, authored by experts in China and the United States, Wulong is one of the earliest velociraptor relatives and potentially a missing link in the dinosaur-to-bird evolutionary transition.

Wulong bohaiensis, a name that means “Dancing Dragon” in Chinese to reference its active pose. Credit: Ashley Poust.

The dinosaur was about the size of a raven, but double its length, and looked like a dwarfish feathered raptor. Its four limbs must have looked like wings, all balanced by a very long, double-plumed tail. Feathered limbs and tails are what we associate today with modern birds.

Although tiny, Wulong had a fierce-looking narrow face and its mouth was littered with sharp teeth. Its bones were small and light, like a bird’s.

Not too long ago, feathers were thought to have appeared exclusively in birds. However, we now know that many dinosaurs species — the ancestors of today’s birds — had a plumage of some sort. In fact, many key avian features may have evolved even before dinosaurs appeared, in a common ancestor.

Wulong skull. Credit: The Anatomical Record.

Writing in the journal The Anatomical Record, the team of researchers claims that the new dinosaur looks very closely related to the origin of birds.

When it died, the dinosaur was a juvenile, based on its bones that had not fully matured. The feathers, however, resemble those of a mature adult, suggesting that they grew much more quickly than bones, unlike modern birds. It’s possible that the young Wulong needed these tail and limb feathers for some yet unknown purpose.

Jehol biota, the richest fossil deposits in the world and the Chinese region where Wulong was found, was probably one of the most biodiverse habitats for early flying animals. It housed birds, bird-like dinosaurs, and even pterosaurs. Around this time some of the first flowering plants began to bloom.

“There was a lot of flying, gliding, and flapping around these ancient lakes,” says Poust. “As we continue to discover more about the diversity of these small animals it becomes interesting how they all might have fit into the ecosystem.”

“It was an alien world, but with some of the earliest feathers and earliest flowers, it would have been a pretty one.”

Fossil Friday: teeny tiny T. rexes showcase the predator’s teenage years

New research found that two dinosaur skeletons believed to belong to a previously-unknown species were, in fact, immature tyrannosaurus rexes.

Back in the early 2000s, members from the Burpee Museum of Natural History in Rockford, Illinois collected two fossil skeletons from Carter County, Montana. These specimens, christened “Jane” and “Petey,” were about as tall as a draft horse and about two times as long. Their bones hinted at a predator species but, due to their size, it was believed we were looking at a diminutive relative of the species.

The skull of the juvenile T. rex, “Jane”
Image credits Scott A. Williams.

Now, new research shows that both Jane and Petey were, in fact, teenage tyrannosaurs, aged 13 and 15.

Terrible teens

“Historically, many museums would collect the biggest, most impressive fossils of a dinosaur species for display and ignore the others,” said Holly Woodward, a Ph.D. at Oklahoma State University Center for Health Sciences, who led the study.

“The problem is that those smaller fossils may be from younger animals. So, for a long while we’ve had large gaps in our understanding of how dinosaurs grew up, and T. rex is no exception.”

The team looked within the fossilized bones to determine the age at which these animals died. This technique is known as paleohistology and involves the analysis of bone microstructures of a particular specimen to determine how fast it grew and at what age it stopped. To do this, the team took thin slices from the leg bones of both specimens and investigated them at high magnification.

Cyclical growth marks resembling tree rings in a femur and tibia bone from the specimens.
Image credits Woodward et al., (2020), Science Advances.

Jane and Petey met their end at 13 and 15 years old, respectively, the team reports. Determining their age also helped clarify the issue of species as well. Previously, the fossils were believed to belong to a pygmy relative of the tyrannosaur known as Nanotyrannus.

The research does help us better understand the lives of these immense predators. Woodward points out that it took T. rex up to twenty years to reach adult size, and as such they probably experienced dramatic physical changes as they matured. She adds that Jane and Petey, being juveniles, were likely lightning-fast and used their sharp, blade-like teeth to tear flesh. Adults, on the other hand, were likely much more cumbersome and used their massive jaws to crack open bones through sheer force.

One interesting find the team made is that T. rex could work around periods with scarce food by simply not growing as much. When food became plentiful again, it would grow rapidly, they add.

“The spacing between annual growth rings record how much an individual grows from one year to the next. The spacing between the rings within Jane, Petey, and even older individuals is inconsistent — some years the spacing is close together, and other years it’s spread apart,” said Woodward.

Still, as evidenced by their growth spurts, even in early life T. rex was a formidable predator.

The paper “Growing up Tyrannosaurus rex: histology refutes pygmy ‘Nanotyrannus’ and supports ontogenetic niche partitioning in juvenile Tyrannosaurus” has been published in the journal Science Advances.

Dinosaur feathers were crawling with lice, amber fossils show

Modern birds are often plagued by feather-chewing lice and, according to a new study of two amber fossils, their dinosaur ancestors weren’t spared, either.

 Mesophthirus angeli feeding on dinosaur feathers. Credit: Nature Communications.

Paleontologists from the Capital Normal University in Beijing recently described a louse-like insect, which they’ve named Mesophthirus engeli, based on individuals trapped in two pieces of Burmese amber.

The insect lived around 100 million years ago during the mid-Cretaceous. The same amber fossil also contained damaged feathers, which by the looks of them, seem to have been chewed by the ancient lice. This makes it the oldest evidence yet of insects feeding on feathers.

Mesophthirus angeli resembles modern lice. Credit: Nature Communications.

Previously, researchers showed that dinosaurs had all sorts of parasites pestering them, from fleas to ticks. Adding lice to the list isn’t that much of a surprise. What was surprising, though, was their relatively small size. The researchers believe that adults measure about 0.5mm in length, which is very small compared to other ectoparasites from that era, like fleas.

The previous record-holder for the oldest feather-munching insect belonged to Megamenopon rasnitsyni, a 44-million-year-old ancient bird louse. The new findings extend this parasitic behavior by another 55 million years.

Mesophthirus engeli had many features common in modern lice, including teeth, short, study antennae, and a thick, wingless body. Their feedings patterns also seem similar. When the researchers examined one of the feathers traped in amber under a microscope, they found holes toward its end, but not near the base — this is how modern lice feed on feathers, too.

“This finding demonstrates that feather-feeding behaviours of insects originated at least in the mid-Cretaceous, accompanying the radiation of feathered dinosaurs including early birds,” the authors wrote in Nature Communications.

Modern bids have the ability to molt, which enables them to replace old or damaged feathers. The new study may explain how molting evolved, also suggesting that lice evolved alongside the development of feathers.

Fossil Friday: paleontological trove shows how mammals took over from the dinosaurs

More than 40 mammal skulls have been dug out of Corral Bluffs, a fossil site in Colorado. Credit: HHMI TANGLED BANK STUDIOS

One gloomy day about 66 million years ago, disaster struck our planet. That day, an asteroid hit offshore Mexico’s Yucatan peninsula with the force of 10 billion Hiroshima bombs. As a result of the devastating impact, 75% of all animal and plant species became extinct — including all non-avian dinosaurs.

But, in the wake of the dinosaurs’ downfall, a new lineage was ready to fill in the ecological void and dominate the globe’s surface. How exactly mammals swept in during these chaotic times, however, has always been somewhat of a mystery since the fossil record in the first million years after the asteroid impact is rather poorly documented.

The discovery of a trove of exceptionally preserved fossils might change all that. Paleontologists have recently described the remains of 16 mammalian species, as well as turtles, crocodilians, and plants, encased in hundreds of fossils unearthed in Colorado.

Corral Bluffs, near Colorado Springs. Credit: HHMI TANGLED BANK STUDIOS

The unlikely find comes from a site at Corral Bluffs, an outcrop in the Denver Basin, just east of Colorado Springs, not famous at all for fossils. But Tyler Lyson, a paleontologist at the Denver Museum of Nature and Science, struck gold there, finding an array of mammalian species that lived from a couple of thousand years to a million years after the killer asteroid impact.

“I split open a concretion and saw a mammal skull smiling back at me,” Lyson said. “And then I looked around and saw concretions just littering the landscape and was like, ‘oh man, here we go.’ Sure enough, we found like four or five mammal skulls within a few minutes. That was one of the most remarkable moments in my life.”

These fossils showed the remarkable growth spurt that mammalians went through after they were free to occupy ecological niches previously dominated by dinosaurs. While the biggest mammal that escaped the mayhem weighed no more than a pound (0.5kg), just 100,000 years later there were 13-pound (6-kg) specimens. Another 200,000 years later, the largest mammals had triple that weight.

Pictured: Loxolophus, a raccoon-sized omnivorous mammal that thrived only 300,000 years after the asteroid impact. HHMI TANGLED BANK STUDIOS

And it wasn’t just the demise of dinosaurs that helped mammals. The asteroid impact also changed the plant landscape, with trees from the walnut family becoming more common, replacing the previously palm tree-dominated landscape. This was very advantageous to early omnivorous mammals, who could now supplement their insect diet with more nutritious plant-based protein.

The largest mammal from this time period was Carsioptychuswhich is a distant relative of today’s hoofed mammals.

“Its premolars were very large and flat, with many weird folds, so there has always been speculation they may have fed on hard objects, such as the nuts trees in this family produce,” Lyson told National Geographic.

Another 400,000 years later, some mammals could weigh over a hundred pounds (45 kg). This period, the researchers noted, coincides with the appearance of the first plants from the bean family, whose leaves and protein-rich seed pods helped many herbivores thrive.

Besides free ecological niches and new nutritional sources, the rise of the mammals may have also been accelerated by three periods of significant warming in the million years after the mass extinction.

The idea that mammals quickly recovered after the most recent mass extinction and grew rapidly in size is not new. Where this new study shines, however, is in the fine details that describe how this transition went about. What’s more, this may just be the beginning. The newly described fossils come from a single geographical site, but there’s much to learn by including more diverse sites. Finding specimens that lived close to the post-asteroid period is not easy, but there is now a new impetus to look for them.

The findings appeared in the journaScience. A one-hour documentary produced by NOVA about the discovery, called “Rise of the Mammels” will also be available to stream on the PBS site and will air on PBS the evening of October 30.

Fossil Friday: the marine lizards mosasaurs used to do the breast stroke, study showed

Frequently described as sea monsters, the mosasaurs were marine lizards that existed during the late Cretaceous seas. They had powerful jaws, two rows of sharp teeth and could grow up to fifty feet. But, those weren’t there only advantages, according to a new study.

Credit: Wikipedia Commons

Research at the University of Southern California showed mosasaurs had a muscular breast stroke that may have added ambush-worthy bursts of speed, a feature unknown before.

“We know that mosasaurs most likely used their tails for locomotion. Now we think that they also used their forelimbs, or their tail and forelimbs together,” explains lead author Kiersten Formoso, a Ph.D. student in vertebrate paleontology. That dual swimming style could make mosasaurs unique among tetrapods (four-limbed creatures), living or extinct, she said.

In the past, other studies showed mosasaurs had an unusually large pectoral girdle — the suite of bones that support the forelimbs. But most assumed the creature’s swimming was mainly driven by their long tails, something like alligators or whales. That swimming style is called “cruising,” as opposed to “burst” motion.

“Like anything that swims or flies, the laws of fluid dynamics mean that burst versus cruising is a tradeoff,” said co-author Mike Habib, Assistant Professor of Anatomical Sciences at USC. “Not many animals are good at both.”

Seeking to look more at whether mosasaurs were burst-adapted, cruise-adapted or a balance of both, Formoso and her team focused on the oversized pectoral girdle. They studied a fossil Plotosaurus, a type of mosasaur, and used measurements of mosasaur pectoral girdles published in other studies.

The study determined that the mosasaurs’ unusually large and low-placed pectoral girdle supported large muscle attachments. In addition, asymmetry in the bone structure is a telltale sign of the strong, inward, pull-down motion called adduction. This suggests that mosasaurs used their forelimbs to swim, breast-stroke style, adding powerful bursts of propulsion to their ability to cruise.

For the team, the next step will be to model bone structure, morphology, measurements, and fluid dynamics (such as drag) to learn exactly how, and how fast, these sea monsters swam. Along with applications to biomechanics, and even robotics, the study also sheds light on how evolution and ecosystems are affected by fluid dynamics.

Formoso and the rest of the team pointed out that it’s a challenge to study kinematics on extinct animals, considering that the subjects are missing flesh, skin, and many bones. But, one thing is nearly certain, she said. “Mosasaurs swam unlike anything else.”

Artist rendering of Chicxulub impact. Credit: NASA

Scientists reconstruct the first 24 hours of dinosaur-killing asteroid impact

This painting by Donald E. Davis depicts an asteroid slamming into tropical, shallow seas of the sulfur-rich Yucatan Peninsula in what is today southeast Mexico.

One gloomy day, about 66 million years ago, disaster struck our planet. That day, an asteroid hit offshore Mexico’s Yucatan peninsula with the force of 10 billion Hiroshima A-bombs. In the wake of the devastating impact, 75% of all animal and plant species became extinct — including all non-avian dinosaurs.

Now, scientists have reconstructed the horrendous first 24 hours that created the massive 180-kilometer-wide Chicxulub crater in Mexico. Immediately, the impact triggered wildfires, huge tsunamis, and released millions of tons of sulfur that blocked the sun, eventually leading to global cooling.

This tragic event has remained etched permanently in the planet’s geological history, through a band called the K-T Boundary, which separates the Cretaceous and Tertiary periods in geologic history.

Oddly enough, the crater was discovered only twenty years ago. Previously, scientists called to attention a thin layer of iridium that could be found in rocks all over the world and dated around the time of the dinosaurs’ demise. This material is extraterrestrial, typically found in asteroids, but also in some volcanic ejections. In 1991, Alan Hildebrand, a geologist at the University of Calgary in Canada, found shocked quartz and a layer of iridium-enriched dust in samples collected in the 1950s by Mexican geologists looking for oil at the Chicxulub, and this ultimately led to finding the crater.

In the 25 years since the asteroid’s impact point was identified, scientists have learned a lot about how this event altered the planet.

In 2017, British researchers at Imperial College London estimated that the asteroid collision released about 325 gigatons of sulfur and 425 gigatons of carbon dioxide into the atmosphere, more than 10 times global human emissions of carbon dioxide in 2014. The asteroid crashed into the Earth with the explosive force of 40,000 US nuclear warheads, all triggered in a matter of seconds.

According to that study, Earth’s average surface air temperature dropped by as much as a staggering 26 degrees Celsius (47 degrees Fahrenheit). The sub-freezing temperatures persisted for over three years — enough to destroy plant life and everything else up the food chain.

But the most grueling moments were right after the impact. Writing in the journal Proceedings of the National Academy of Sciences, researchers have reconstructed the timeline of the first day of the dinosaurs’ doom.

The team led by Sean P. S. Gulick, a marine geophysicist at the University of Texas at Austin, utilized high-resolution photography, microscopy, computed tomography imaging and magnetic measurements of sedimentary rock recently recovered from Chicxulub.

Geologists read sediment layers like pages in a history book. Normally, a few centimeters of rock corresponds to a couple thousand years. What scientists recovered at Chicxulub is a 130-meter layer for a single day — imagine the scale of destruction unleashed by the killer asteroid.

“We fried them and then we froze them,” Gulick said in a statement. “Not all the dinosaurs died that day, but many dinosaurs did.”

At ground zero, the asteroid initially carved a 100-km-wide (60-mile), 32-km-deep (20-mile) hole and catapulted rock into the sky with such force that some of it must have reached the moon. Immediately, a huge tsunami was triggered moving radially away from the crater. But half an hour later, the water started moving in the opposite direction, back into the crater, flooding it with debris.

“Most of the material that filled the crater within hours of impact was produced at the impact site or was swept in by seawater pouring back into the crater from the surrounding Gulf of Mexico,” the researchers explained. “Just one day deposited about 425 feet of material — a rate that’s among the highest ever encountered in the geologic record.”

Besides tsunamis and an apocalyptic cloud of sulfur that rained molten rock, the asteroid impact also triggered massive forest fires across the globe. This is evidenced by charcoal in the peak ring above the tsunami layer.

“This suggests that the charred landscape was pulled into the crater with the receding waters of the tsunami,” the researchers noted.

In the future, the researchers plan on studying more potential pieces of evidence from the immediate aftermath of the impact in order to better reconstruct the early hours of dinosaur doom.

Research suggests T. rex had a cooling system in its head

The Tyrannosaurus rex, the most feared and iconic of all the dinosaurs, had a cooling system in its skull that allowed him to deal with prehistoric heat and humidity. The new study from scientists in Missouri, Ohio, and Florida, challenges previous beliefs about this cranial structure.

Credit: Wikipedia Commons

T. rex, known as one of the largest meat-eating dinosaurs on the planet, has two large holes in its skull, called the dorso-temporal fenestra — basically two “windows” in the back of its head. Scientists used to believe that they were filled with muscles that helped with jaw movements but now this was challenged by a new study.

Similar holes can be found in the skulls of a class of animals known as diapsids, an extremely diverse set of animals grouped together because of this particular feature (this class includes not only crocodilians, but also birds, lizards, and tuatara). The holes are thought to have evolved about 300 million years ago.

“It’s really weird for a muscle to come up from the jaw, make a 90-degree turn, and go along the roof of the skull,” Holliday said. “Yet, we now have a lot of compelling evidence for blood vessels in this area, based on our work with alligators and other reptiles.”

Researchers looked at alligators at the St. Augustine Alligator Farm Zoological Park in Florida, using thermal imagining to translate heat into visible light. The new evidence obtained offers a new theory and insight into the anatomy of a T. rex’s had, they argued.

Because alligators are cold-blooded (or ectothermic) their body temperature is dependent on the temperature of their environment. This means that their thermoregulation processes are very different from warm-blooded, or endothermic, organisms.

“We noticed when it was cooler and the alligators are trying to warm up, our thermal imaging showed big hot spots in these holes in the roof of their skull, indicating a rise in temperature. Yet, later in the day when it’s warmer, the holes appear dark, like they were turned off to keep cool,” said Kent Vliet, coordinator of laboratories at the University of Florida’s Department of Biology.

The researching team worked with the thermal imaging data to examine fossilized remains of dinosaurs and crocodiles, trying to understand how this hole in the skull changed over time.

“We know that, similarly to the T. rex, alligators have holes on the roof of their skulls, and they are filled with blood vessels,” said Larry Witmer, professor of anatomy at Ohio University’s Heritage College of Osteopathic Medicine. “Yet, for over 100 years we’ve been putting muscles into a similar space with dinosaurs. By using some anatomy and physiology of current animals, we can show that we can overturn those early hypotheses about the anatomy of this part of the T. rex’s skull.”

It’s not yet known whether dinosaurs in general and T. rex in particular, were ectothermic or endothermic. The topic is actually under debate, with some scientists thinking the former, some the latter, and some believing dinosaurs fell somewhere between the two – a feature called mesothermy.

Nevertheless, what the new research published in the journal The Anatomical Record, suggests is that T. rex and other dinosaurs used some of the thermoregulation tactics of ectotherms. The actual meaning of this within the broader context of their metabolisms is yet to be explored.