The teeth of T. rex and other large theropods were likely covered in scaly lips, concludes a study published earlier this week by the journal Science.
The dinosaur’s teeth did not protrude when its mouth was closed, the authors write, and even when it opened it wide to bite, only the tip could be seen.
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This study is the latest chapter in the long-running debate about what dinosaur mouths look like.
Recent images show large teeth protruding from the dinosaurs’ jaws, even when they are closed. Some believed the teeth of predators were simply too big for their mouths, said study author, paleontologist Thomas Cullen of Auburn University in Alabama.
When researchers compared the skulls of dinosaurs to those of modern reptiles, however, they found that was wrong. The teeth of large monitor lizards may actually be larger than those of tyrannosaurs compared to the size of their skulls, but they can still hide them under scaly lips, Cullen said.
The researchers also found clues by examining the wear of the teeth.
For creatures like the crocodile, whose teeth protrude from the mouth, the exposed part of the tooth wears down quickly ― “like someone ran a sandblaster down the side of the mouth,” said another author of the study, Mark Witton of Britain’s University of Plymouth.
But when researchers examined a tooth from a daspletosaurus, a cousin of t. rex., they found it to be in good condition with no uneven wear.
With this evidence and other clues from dinosaur anatomy, the study makes a strong case for the tyrannosaur lip hypothesis, said Thomas Holtz, a University of Maryland paleontologist who was not involved in the studies. works.
That being said, he added, “we’re not talking about lips for kissing,” since they would have been thin and scaly, like those of the Komodo dragon.
This isn’t the first time the popular image of dinosaurs has been challenged. Previous studies have shown that the tyrannosaurus had a more arched back than is believed, and that the fearsome velociraptors probably had feathers.
Most of what is known about dinosaurs comes from their bones; it can be difficult to get clear answers about their soft tissues like skin, which are usually not fossilized.
Adding lips makes the dinosaurs a little less ferocious, but it also makes it more realistic, Witton believes.
“You don’t really see a monster,” he said. We see an animal.