T-rex with lips? Here is what you need to know

Palaeontologists have given one of the most famous dinosaurs a makeover, proposing that the Tyrannosaurus or the T-rex did not sport ferocious, protruding chompers but rather proportionally sized teeth concealed by a set of scaly, lizard-like lips. The revelation about T-rex with lips threatens to ruin some childhood toys or the experience of rewatching Jurassic Park.

An international team of researchers from the University of Portsmouth examined the jaw morphology, tooth structure, and dental wear patterns of lipped and lipless reptiles. They discovered that contrary to older theories, T-rex lips were more similar to those of lizards than crocodiles.

“Although it’s been argued in the past that the teeth of predatory dinosaurs might be too big to be covered by lips, our study shows that, in actuality, their teeth were not atypically large,” the study's lead author Thomas Cullen, assistant professor of paleobiology at Auburn University. 

“Even the giant teeth of tyrannosaurs are proportionally similar in size to those of living predatory lizards when compared for skull size, rejecting the idea that their teeth were too big to cover with lips," he added.

In fact, according to the researchers, their jaw anatomy was similar to that of a tuatara, a diminutive extinct reptile from New Zealand that is related directly to the dinosaurs. 

Co-author Derek Larson, Collections Manager and Researcher in Palaeontology at the Royal BC Museum in Canada said that it was "remarkable" how similar T-rex lips are to monitor lizards.

According to the findings, the dinosaurs' teeth and skulls were comparable in size to those of contemporary lizards with lips. The pores in the theropod jaws that would have contained the nerves and blood for the mouth tissue were much more like those in a lizard than a crocodile, according to fossil analysis.

Co-author Kirstin Brink, assistant professor of palaeontology at the University of Manitoba, said that if teeth are not covered by lips, there is a risk of them drying out, and this can also cause more damage during eating or fighting, the way we see it in crocodiles.

“Dinosaur teeth have very thin enamel and mammal teeth have thick enamel (with some exceptions),” she added. 

While the discovery offers novel insights into how the T-rex may have nourished and preserved dental health, it also opens up some fascinating new research directions for evolutionary ecologists and the opportunity of starting over for artists.

The research was published in the journal Science.