Tag Archives: tyrannosaurus rex

Researchers investigate intriguing ‘baby’ tyrannosaur fossil

The “fabulous” fossil probably belongs to a young Tyrannosaurus rex that lived 66.5 million years ago — but it also could also be a mature specimen of a smaller carnivorous dinosaur.

Back at the lab, the researchers found the fossil glowed under a black light. Credit: University of Kansas.

Tyrannosaur fossils are always a treat, but finding one as well-preserved as this one is a special treat. The fossil features a complete section of the upper jaw with all of its teeth intact, along with bits of the specimen’s skull, foot, hips and even backbone. Judging by the preliminary analysis, the fossil seems to belong to a juvenile, which means it could offer new perspectives on how tyrannosaurs evolved and developed — but it also means more questions.

Whenever you’re working with fossils that are tens of millions of years old, you’re bound to deal with some uncertainties. The Nanotyrannus (as the specimen has been named) is hard to attribute to one species or another because not many juvenile fossils have been found.

“The teeth suggest it’s a Tyrannosaurus rex; however, there is still more work to be done,” said David Burnham, preparator of vertebrate paleontology at the KU Biodiversity Institute. “Because a young T. rex is so rare, there are only a few that have been found over the years, so it’s difficult to discern what are changes due to growth or if the differences in the bones reflect different species. Fortunately, KU has an older T. rex to compare with and another young T. rex on loan to help decipher this problem.”

Many animals show growth lines in their bones as they are developing — kind of like tree rings. However, as the bone ages and is potentially damaged, regular repair procedures are carried out to renew bone, and these procedures can mask each other, hiding the real age of the bone.

In this case, researchers are planning a microscopic analysis of the fossil bones that were brought into the lab, and they’re also preparing for a new trip to the original fossil site to see if they can find more of it.

“Confusing the issue here is age,” Burnham said. “Ontogeny, that’s the process of growth—and during that process we change. Adult dinosaur bones, especially in the skull, don’t look the same as their younger selves. So, if someone finds a baby or juvenile fossil they may think it’s a new species, but we have to be careful since it may represent a younger growth stage of an existing species. It’s reasonable to assume Nanotyrannus could be valid—but we must show it’s not just a stage in the life history of T. rex.”

After the analysis concludes, we can expect a paper addressing the position of this fossil on the family tree of theropod dinosaurs and answering the most pressing of questions: was it a T-Rex, or not.

T-Rex’s image as a giant, scaly, monster supported by new study

Recent studies have cast some doubt on the general appearance of the Tyrannosaurus Rex; sure, it was a giant, hell-like predator, that’s for sure, but was it covered in feathers, scales, or did it have some kind of mix or transitional skin? Well, a new study restores the ‘traditional’ image of the T-Rex, concluding that the dinosaur was, at least mostly, covered in scales.

Petting a T-Rex

This fossilized skin comes from the neck of a Tyrannosaurus rex. Image credits: Peter Larson.

Scott Persons, a paleontologist at the University of Alberta, has been fascinated by dinosaurs since he was a little boy. Luckily, he was able to turn that fascination into a career, and now, in a study published in Biology Letters, he offers a valuable contribution to our understanding of dinosaurs. Persons and his colleagues analyzed newly-found skin impressions found in Alberta, Canada, not only from T-Rex, but also from other tyrannosaur species including Albertosaurus, Daspletosaurus, Gorgosaurus, and Tarbosaurus. They found several intriguing samples and identified a common pattern between them: all skin impressions had a texture riddled with small pebbly scales and not fuzzy plumage.

This contradicts previous studies, which found that T-Rex sported a rich feathery plumage. This new study doesn’t necessarily disprove that, it just seems to suggest that at least some (perhaps most) of tyrannosaurs were covered in scales.

“Now that we’ve found these multiple patches of preserved tyrannosaur hide from multiple places across the body, it looks pretty clear that at least the majority of the T. rex was not covered in feathers,” says Persons.

This also doesn’t mean that they were completely devoid of feathers, just that feathers weren’t the dominant feature on their skin. So if you were to pet a T-Rex (something which thankfully, you can’t), it would feel much like a reptile living today. You might or might not stumble upon some plumage, but mostly, it would just be scales.

A scaly situation

This fossil skin sample used in the study comes from a T. rex tail. Image credits: Peter Larson.

This raises an interesting question. We know that T-Rex’s ancestors developed feathers through evolution, why would T-Rex shed them? It seems counterintuitive to develop a feature and then shed it, only to re-develop it again.

Dr. Steve Brusatte, a paleontologist from the University of Edinburgh, who was not involved in the study, commented on this, telling the BBC that this might have happened due to the sheer size of the dinosaur. For instance, Asian elephants are hairier than African elephants, because they are smaller and live in dense forests, with dim sunlight. Just as the larger African elephants grew larger and shed some of their hair, this might also be the case with T-rex and its ancestors.

“But I don’t think we can assume that T. rex lacked feathers just because some fossil skeletons have skin impressions that are scaly,” he added. “It takes inconceivable good luck to preserve feathers in fossils. Just because we don’t see them doesn’t mean they weren’t there. So I don’t think we need to throw out the image of a big fluffy T. rex quite yet.”

Persons agrees with this possibility and says there might be a similar mechanism at work, with today’s mammals.

“If you think about really, really big terrestrial mammals today, like elephants, rhinos, hippos, and cape buffaloes, although they are not hairless, they are very much reduced in the amount of hair that they do have,” says Persons.

Journal Reference: Phil R. Bell, Nicolás E. Campione, W. Scott Persons, Philip J. Currie, Peter L. Larson, Darren H. Tanke, Robert T. Bakker — Tyrannosauroid integument reveals conflicting patterns of gigantism and feather evolutionDOI: 10.1098/rsbl.2017.0092

Meet ‘Pinocchio rex’ – the 9 meter long, ferocious cousin of Tyrannosaurus Rex

A new type of Tyrannosaur with a very long “nose” has been nicknamed “Pinocchio rex” – but this dinosaur was nothing to laugh about. It measured some 9 meters in length, was a ferocious carnivore, and had a long, distinctive snout – which possibly made it even more dangerous.

Artistic depiction of “Pinocchio Rex”

Interestingly enough, the skeleton was found at a construction site in China, and was identified and reconstructed by scientists at Edinburgh University, UK. The 66 million year old predator officially named Qianzhousaurus sinensis, is described in Nature Communications.

“Pinocchio” looked very different to other tyrannosaurs. It had the familiar toothy grin of T. rex, but its snout was long and slender, with a row of horns on top,” said Edinburgh’s Dr Steve Brusatte. It might have looked a little comical, but it would have been as deadly as any other tyrannosaur, and maybe even a little faster and stealthier. We thought it needed a nickname, and the long snout made us think of Pinocchio’s long nose.”

Researchers believe several different tyrannosaurs competed side by side in what is today China during the Cretaceous period. The enormous Tarbosaurus (up to 13m) was extremely strong, being able to overpower most of the giant herbivores which inhabited the area. Pinocchio Rex was lighted, and probably fed off of smaller creatures, such as lizards and feathered dinosaurs. But at 9 meters and almost a ton – it was still huge.

“The iconic picture of a tyrannosaur is T. Rex, the biggest, baddest dinosaur of all. “But this new species was lighter, less muscular. It breaks the mould. Perhaps it had a faster bite and hunted in a different way.”

But why did it have such a big, elongated snout – 35 percent longer than any tyrannosaur?

“The truth is we don’t know yet. But it must’ve been doing something different,” Dr Brusatte explained.

In recent years, two juveniles from the same species were dug up, raising the first questions about a new tyrannosaur.

“The trouble was, they were both juveniles. So it was possible their long snouts were just a weird transient feature that grows out in adults,” said Dr Brusatte, an expert in tyrannosaur evolution.

But this one is an almost mature dinosaur, almost 2 times bigger than previously excavated specimens, and confirms hunches about the large snouts – it also seems to suggest that Pinocchio Rex wasn’t an isolated species, and in fact, was quite widespread in what today is Asia.

“Although we are only starting to learn about them, the long-snouted tyrannosaurs were apparently one of the main groups of predatory dinosaurs in Asia,” he said.

It’s settled – Tyrannosaurus Rex hunted for live prey

The king of all predators, the godfather of his time, la creme de la creme – Tyrannosaurus Rex (T. Rex) was the ultimate predator… or was he? When Jurassic Park came out, even though the cinema crowd went wild as T. Rex smashed and ate velociraptors (and the occasional human), at the time, there was no compelling proof that the dinosaur actually hunted – some teams actually claimed that he was a scavenger.

trex

In 2011, a team from the Zoological Society of London reaffirmed T. Rex as the mean green killing machine we all know:

“It is effectively impossible for Tyrannosaurus rex to have fed solely or almost completely on carcasses of dead animals. T. rex lived in an ecosystem with a large number of smaller-bodied carnivorous dinosaur species and it couldn’t have relied on carcasses for its diet,” said Sam Turvey, a co-author of the study published in Proceedings of the Royal Society B.

It seemed obvious that T. Rex was a hunter. But few doubts still remained. Now, another study seems to pin the final nail in the scavenger theory.

The researchers found a T. rex tooth stuck between vertebrae in the tail of a herbivorous duck-billed hadrosaur. The fossils came from a famous area in South Dakota – the Hell Creek Formation.

This CT scan of a duck-billed hadrosaur's vertebra shows an embedded T. rex tooth crown with bone tissue that regrew around it.

This CT scan of a duck-billed hadrosaur’s vertebra shows an embedded T. rex tooth crown with bone tissue that regrew around it.

The finding is very significant because the T. rex tooth is surrounded by bone that clearly grew after the tooth became lodged there. This could only happen if the predator bit the herbivore’s tail, lost its tooth there, as well as the prey.

“It’s a smoking gun. We finally have Tyrannosaurus rex caught in the act,” says Bruce Rothschild, a palaeopathologist at the University of Kansas in Lawrence and a co-author of the paper. “We’ve seen plenty of re-healed bite marks attributed to Tyrannosaurus rex, but it’s hard to confirm identity with those,” says Thomas Holtz, a vertebrate palaeontologist from the University of Maryland in College Park. “Actually having the broken tooth makes it easy to determine who was doing the hunting here,”

But even with this, some are hard to convince.

“I’ve long argued that Tyrannosaurus rex was an opportunist like a hyena, sometimes hunting and sometimes scavenging. This provides no evidence to the contrary,” says Jack Horner, a palaeontologist at the Museum of the Rockies in Bozeman, Montana, who served as scientific adviser on the Jurassic Park films.

But even as a few argue that he wasn’t a pure predator, and more argue that he in fact was, even a larger group is just fed up by this debate.

“Great galloping lizards!” exclaims John Hutchinson, an evolutionary physiologist at the Royal Veterinary College in London. “It is so frustrating to see provocative half-baked ideas about celebrity species like Tyrannosaurus rex drawing the public’s attention when there is so much more interesting palaeontology to be talking about.”

Via Nature

Carnotaurus had puny arms, incredibly powerful tail

If you think that T-Rex had laughable front limbs, you’re in for a treat: even he would be amused by upon such puny arms. However, the shortcomings Carnotaurus had more than made up for its very muscular and powerful tail, which made it one of the fastest hunters to ever walk the face of the Earth.

Measuring over 8 meters long, Carnotaurus ruled South America, while T-Rex was ‘in charge’ of Asia and North America; the dinosaur had razor sharp teeth that fitted in quite nicely with its amazing hunting abilities. Tail bone fossils reveal that a particular muscle known as the caudofemoralis was attached by a tendon to the upper leg bones; when the tail moved, it gived a momentum to the back legs, which led to remarkable and fearsome strides – a feat it wouldn’t have been capable otherwise.

Brian Murphy from the University of Alberta conducted the study. His examination of the tail showed that along its length were pairs of tall rib-like bones that interlocked with the next pair in line. Using 3-D computer models, Persons recreated the tail muscles of Carnotaurus. He found that the unusual tail ribs supported a huge caudofemoralis muscle. The interlocked bone structure along the dinosaur’s tail did present one drawback: the tail was rigid, making it difficult for the hunter to make quick, fluid turns. Persons says that what Carnotaurus gave up in maneuverability, it made up for in straight ahead speed. For its size, Carnotaurus had the largest caudofemoralis muscle of any known animal, living or extinct.

Via io9