[Animals] The jaws of the 'Tyrannosaurus rex' were protected by lips similar to those of lizards

[HeWhoRemains™]

A fierce decades-long debate between paleoartists and scientists seems to be coming to an end: Tyrannosaurus rex had lips. Or, failing that, a soft tissue that covered and moistened their teeth, as well as protecting them from the outside. Thus, their profile representation is less similar to that of contemporary crocodiles, famous for their jaws with outward fangs, and could be more closely related to living lizards.

The new research that clarifies this mystery has been led by Robert Reisz, a paleontologist at the University of Toronto (Canada), specializing in the study of the evolution of tetrapods. His work, recently published in the scientific journal Science, thus puts an end to one of the most iconic representations of dinosaurs, as is the case of the T-Rex and its association with the already mythical Jurassic Park saga (1993), directed by Steven Spielberg. based on the work of scientist and science fiction writer Michael Crichton.

 

Despite the film's po[CENSORED]rity in the po[CENSORED]r imagination, discussion of dinosaur lips dates back to at least the 19th century. “There is a cultural fascination with T-Rex being ferocious monsters and for us that means long teeth,” the biologist clarifies with a smile from his home in Toronto, in a videoconference interview. And he ventures: "Now I think that, in my opinion, even when they opened their mouths, the fangs of the T-Rex would not stick out as much."

In this way, the researchers hope to settle a decades-long discussion between artists specialized in scientific illustration and academia, with the invaluable distortion that po[CENSORED]r culture has caused around the fascinating figure of one of the best-known dinosaurs, even generating children's figures with upper teeth always visible.

There's a cultural fascination with T-Rexes being ferocious monsters, and to us that means long teeth.

For the scientists, one of the key pieces was the prehistoric dental record: the fangs of the saurians did not break like those of the crocodiles. The enamel of the teeth requires hydration so that it does not break, as in the case of alligators, which always have theirs exposed, even with their jaws closed. Although they spend much of their time submerged underwater, examination of their strong, pronounced tusks reveals cracks and deterioration on their surface.

Reisz's work indicates that this is not the case of dinosaurs, since the available data indicates that they must have protected and protected their teeth in some way, since their enamel is much finer than that of crocodiles. The biologist considers that the fangs of the lizards would have to present a very characteristic degradation if they had suffered constant exposure to the environment. By comparing them with those of other animals, with and without lips, they realized that those teeth could not have been out in the open millions of years ago.

The anatomy of the skull points to fangs in the right proportion, similar to those of a cat; Otherwise, they couldn't even close their jaws.
Robert Reisz, paleontologist at the University of Toronto (Canada)
The lead author of the study says that even the way the dinosaurs' teeth were broken was more of a closed jaw type than an exposed one. “When you look at some classic representations, you realize that if those teeth were really like they are seen in po[CENSORED]r culture, T-Rexes couldn't even close their mouths,” Reisz details. The paleontologist develops how in the study they compare the maxillary morphology of dinosaurs and come to the conclusion that the upper row of teeth would crush the lower one and the jaw would dislodge. This is how the research rejects the idea of jaws like those of crocodiles and traces a similarity between the scaly-lipped oral barrier, a match for iguanas and lizards, as is the case of Komodo dragons, one of the direct descendants of tetrapods. "Not counting the birds that are the closest living relative, but do not have teeth," the scientist qualifies.

Not satisfied with the main revelation, Reisz elaborates on how his research debunks another myth that has been passed down through po[CENSORED]r culture: T-Rex grimaces would also be impossible. With the cranial reconstructions, the team warns, its jaws could not perform maxillofacial gestures like those we recognize in mammals.

Our research paints a more natural image of T-Rex, making them look less monstrous, yet still fearsome predators.
Robert Reisz, paleontologist at the University of Toronto (Canada)
As with the plumage that is included in the representation of certain dinosaurs, the lips seem to be left in scientifically rigorous images. The authors explain that the study will serve to get an idea of how the oral dynamics or feeding of the dinosaurs were, in addition to improving knowledge about the reconstruction of soft tissues in the excavation of the sites.

“The anatomy of the skull points to fangs in the right proportion, similar to those of a cat; this makes them look less monstrous and gives us a more natural image of the T-Rex”, says Roisz. Although aware of the demystification, he sentences: "They continue to be fearsome predators."

https://elpais.com/ciencia/2023-04-07/las-fauces-de-los-tyrannosaurus-rex-estaban-protegidas-por-labios-similares-a-los-de-los-lagartos.html