Did the T. rex have lips? New findings with B.C. co-author says yes

The Tyrannosaurus rex has been depicted in movies, TV shows and books as a ferocious carnivore – perpetually bearing its teeth at any and all prey.

However, that image may not be entirely accurate.

A new paper, co-authored by Derek Larson, a member of the Royal BC Museum’s palaeontology department, has found that “theropods like Tyrannosaurus rex and Velociraptor may not have had exposed teeth when their mouths were closed, but may have instead had a fleshy covering something similar to lips, not unlike those of modern-day lizards,” according to a release issued by the museum.

Read more: ‘Billions’ of Tyrannosaurus rexes said to have walked the Earth in all of history

“For a long time, researchers have suggested that theropod dinosaurs had exposed teeth, like we see with crocodiles, and this has become the pervasive depiction of predatory dinosaurs in films and documentaries,” said Larson, collections manager and researcher of palaeontology at the Royal BC Museum. “Our study overturns that idea and seriously brings into question how we reconstruct what certain dinosaurs look like.”

Larson worked with an international team of palaeontologists to examine modern examples of lip and tooth structure of animals like the Komodo dragon. From there, the researchers determined that the exposed teeth of crocodiles are unique to their species and that covered teeth – with ‘lips’ – are more typical and therefore, more probable in extinct animals.

“Our study shows that predatory dinosaur teeth were not atypically large,” Dr. Thomas Cullen from Auburn University, the lead author of the study, said in a release.

“Even the giant teeth of tyrannosaurs are proportionately similar in size to those of living predatory lizards, rejecting the idea that their teeth were too big to cover with lips.”

Researchers believe, however, that the lips on dinosaurs would be similar to mobile lips that humans have.

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They also acknowledge that some extinct animals, like various tusked mammals and flying or marine reptiles, almost certainly had exposed teeth, just not T. rex and other predatory dinosaurs.

“Accurately reconstructing an extinct animal has huge implications for inferring the behaviour, diet and evolution of these organisms,” Larson added.

“Palaeontologists 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. Many of the similarities that they once shared with dinosaurs are long gone.”

Read more: The world’s largest T. rex, held in Regina, may have relatives 70 per cent bigger

Given that dinosaurs’ closest modern genetic relatives, crocodiles and birds, are also lipless, Larson says it’s not surprising these depictions have become so prevalent.