Although the T. rex is often depicted sporting a toothy grin as it roams the landscape, its fearsome teeth may actually be hidden behind a pair of thin, scaly lips, research suggests.
Experts say the idea that theropods were beakless arose from the large size of their teeth and the fact that their closest living toothed relatives – such as crocodiles and alligators – lacked beaks.
However, research suggests that, like today’s lizards, theropods may have covered their teeth when their mouths were closed.
Dr Mark Witton of the University of Portsmouth and co-author of the study said popular images of dinosaurs are outdated.
He said, “We’ve been living in the shadow of Jurassic Park for 30 years. “We need to move away from the lipless look of these teeth to things like Tyrannosaurus and toward these animals with more lizard-like faces.”
Writing in the journal Science, researchers from the United States and the United Kingdom say that the tyrannosaurus spent more than 500 days in the mouth of Dyspletosaurus was a major dental experiment. revealed no evidence of significant wear – consistent with studies of other theropod teeth.
In contrast, the large teeth of American alligators are often damaged, and even the dentin layer is worn away—resulting, the researchers suggest, in the animals’ beaklessness, which means their tooth enamel is exposed, causing it to become dry and less resistant. to wear
Witton said that tyrannosaurs often lived more than 12 months before replacing teeth — much longer than crocodiles — adding weight to the idea of ​​the former’s beak.
“No animal can repair or replace worn enamel, and yet tyrannosaurs had thin enamel intact even though some retained their teeth for more than a year,” he said.
The team also found small foramina in the theropod’s jaws that were arranged similar to those of today’s lizards – where they supplied nerves and blood vessels to the lips and gums – while both had vertical teeth, unlike crocodilians whose teeth sloped outwards.
The team said that analysis of the relative size of skulls and teeth in lizards today suggests that theropod teeth were not large enough to be covered by beaks.
“If you imagine a Komodo dragon enlarged with a 5-foot-long skull, it wouldn’t look much different from something like a T-rex,” Witton said.
Professor Steve Brusset of the University of Edinburgh, who was not involved in the work, said that if the researchers were correct, T. rex would have had a gummy smile rather than a toothy smile, adding that soft tissue covers their teeth. Our own are fleshy and will not have the same shape as lips.
However, Brusset said the case is not yet closed. “I suspect (these researchers) are right, and that tyrannosaurs had more soft tissue teeth than crocodilians, but I’m still on the fence about whether their teeth had something to cover them like monitor lizards,” he said.
