A heated, decade-long debate between paleoartists and scientists seems to be coming to an end: Tyrannosaurus rex had lips. Or, failing that, a soft tissue that covers and moisturizes their teeth and protects them from the outside. Therefore, their profile representation resembles less that of contemporary crocodiles, famous for their outward-facing jaws, and may be more closely related to living lizards.
The new research solving this mystery was led by Robert Reisz, a paleontologist at the University of Toronto, Canada, who specializes in studying tetrapod evolution. His work, recently published in the scientific journal Science, puts an end to one of the most iconic depictions of dinosaurs, as in 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.
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Despite the film’s popularity in the public imagination, discussion of dinosaur lips dates back at least to the 19th century. “There’s a cultural fascination that T-Rex are wild monsters, and for us that means long teeth,” the biologist said with a smile from his home in Toronto in a video conference interview. And he dares: “I now believe that in my opinion the fangs of the T-Rex would not stick out that far even with the mouth open.”
In doing so, the researchers hope to settle a decades-long debate between artists specializing in scientific illustration and academia with the invaluable distortion that popular culture has caused around the intriguing figure of one of the most well-known dinosaurs, even bringing about children’s characters with upper teeth always visible.
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 11.6 m long, 3.9 m high and 67 million year old “Tyrannosaurus rex” in Zurich (Switzerland). MICHAEL BUHOLZER (EFE)
One of the key pieces for the scientists was the evidence of prehistoric teeth: the fangs of the dinosaurs did not break like those of the crocodiles. Tooth enamel needs moisture to keep it from cracking, as in the case of alligators, whose enamel is always exposed even when the jaws are closed. Although they spend much of their time underwater, examination of their strong, pronounced tusks reveals cracks and damage to their surface.
Reisz’s work indicates that this is not the case for dinosaurs, as the available data suggests that they must have protected and protected their teeth in some way, as their enamel is much finer than that of crocodiles. The biologist believes that the lizards’ fangs should show a very characteristic deterioration if they had been constantly exposed to the environment. By comparing them to those of other animals, with and without lips, they realized that these teeth could not have been open millions of years ago.
The anatomy of the skull indicates correctly proportioned fangs, similar to those of a cat; Otherwise they couldn’t even close their jaws.
Robert Reisz, paleontologist at the University of Toronto (Canada)
The study’s lead author says that even the way the dinosaurs’ teeth were broken is more consistent with a closed-jaw type than an exposed one. “If you look at some classic depictions, if those teeth were really what they see in popular culture, T. rexes wouldn’t even be able to close their mouths,” Reisz notes. The paleontologist develops how in the study they compare the upper jaw morphology of dinosaurs and conclude that the upper row of teeth would crush the lower one and the jaw would detach. In this way, the research rejects the idea of jaws like those of crocodiles and pursues a similarity between the scaly mouth barrier, a game for iguanas and lizards, as in the case of Komodo dragons, one of the direct descendants of tetrapods. “Excluding the birds, which are the closest living relatives but have no teeth,” the scientist qualifies.
Infographic comparing the different types of skulls, tusks, and lips in the animal kingdom, from the study by Cullen et al.
Not satisfied with the main revelation, Reisz elaborates on how his research debunks another myth passed down through popular culture: T-Rex grimaces would also be impossible. With the skull reconstructions, the team warns, its jaws would not be able to perform maxillofacial gestures like we know them from mammals.
Our research paints a more natural picture of T-Rex, making them look less monstrous but still fearsome predators.
Robert Reisz, paleontologist at the University of Toronto (Canada)
As with the plumage included in the depiction of certain dinosaurs, the lips appear to be left in scientifically rigorous imagery. The authors explain that the study will serve to get a picture of what the oral dynamics, or feeding, of the dinosaurs were like, and to improve knowledge of soft tissue reconstruction when excavating the sites.
“The anatomy of the skull indicates correctly proportioned fangs, similar to those of a cat; It makes them look less monstrous and gives us a more natural image of the T-Rex,” says Roisz. Though aware of the demystification, he judges, “They continue to be fearsome predators.”
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