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

A fierce decades-long debate between paleoartists and scientists seems to be coming to an end:

had lips.

Or, failing that, a soft tissue that covered and moistened your 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

, 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

saga (1993), directed by Steven Spielberg. based on the work of scientist and science fiction writer Michael Crichton.

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Despite the film's popularity in the popular imagination, discussion of dinosaur lips dates back at least to the 19th century.

“There is a cultural fascination with T-Rexes 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 into demystifying him: "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 popular culture has caused around the fascinating figure of one of the best-known dinosaurs, even generating children's figures with upper teeth always visible and eternally

.

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

Robert Reisz, paleontologist at the University of Toronto (Canada)

The skeleton of Trinity, a 'Tyrannosaurus rex' 11.6 m long, 3.9 m high and 67 million years old, in Zurich (Switzerland).MICHAEL BUHOLZER (EFE)

For the scientists, one of the key pieces was to see the prehistoric dental record: the fangs of the saurians did not break like those of the crocodiles.

Tooth enamel requires hydration to avoid chipping, as in the case of alligators, whose teeth are always exposed even with their jaws closed.

Although they spend much of their time submerged underwater, when examining their strong, pronounced tusks, you can see cracks and deterioration on their surface.

Reisz's work points out that this is not the case with dinosaurs, since the evidence indicates that they must have had some way of protecting and safeguarding their teeth, as it is a much finer enamel than that of crocodiles.

For the biologist, when studying the fossils of the lizards, the tusks must have shown a very characteristic degradation of 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 during the Pleistocene.

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 claims that even the way the dinosaurs' teeth were broken corresponded more to a closed jaw type than an exposed one.

"When you look at some classic representations, you realize that if those teeth were really what they are seen in popular culture, T-Rexes couldn't even close their mouths," Reisz details with amazement.

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 draws a similarity between the mouth barrier of scaly lips, a match for iguanas and lizards, as is the case of Komodo dragons,

one of the most direct descendants of tetrapods.

"Not counting the birds that are the closest living relative, but do not have teeth," the scientist qualifies.

Infographic comparing the different types of skull, tusk and lips in the animal kingdom, from the study Cullen et al.

Not satisfied with the main revelation, Reisz elaborates on how his research debunks another myth that has been passed down through popular culture: T-Rex grimaces would also be impossible.

With cranial reconstructions, the team notes, the jaws of the Triassic king 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 inclusion of plumage on certain dinosaurs, the lips appear to remain in scientifically rigorous representations.

The authors explain that the study will serve to get an idea about how the oral dynamics or feeding of dinosaurs were, in addition to improving knowledge about the reconstruction of soft tissues in the excavation of archaeological 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."

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