"Animals like T-Rex, theropod dinosaurs, most likely had some kind of lips, soft tissues covering their mouths to protect their teeth," Thomas Cullen, one of the authors of the study published in the journal Science, told AFP.
"This is a change from many assumptions so far, which were that they looked more like crocodiles, with visible teeth when their mouths were closed and without lips," adds the professor of paleobiology at Auburn University in Alabama, in the south of the United States.
If the question is not totally settled, the researchers studied a panel of theropod dinosaurs from several museums to arrive at this new conclusion.
Scrutinized email
For example, they compared the enamel wear of the teeth of dinosaurs and crocodiles, the living animals closest to these theropods.
Tooth enamel "needs to stay hydrated to stay healthy," Cullen said. "If it's exposed to air for too long, it becomes crumbly and it's more likely to crack or catch disease."
According to the paleobiologist, the enamel on the outer part of the teeth of live crocodiles wears out faster than that present on the inner part because they do not have lips.
"When we looked at the thickness of the enamel on the inside and outside of the teeth of large tyrannosaurs, they didn't have this type of configuration like a crocodile," he continues.
"They present a model closer to animals with lips," says Thomas Cullen. "The thickness of their enamel is the same on the outer and inner sides."
Teeth too big?
The researchers also wanted to know if the T-Rex's teeth could have simply been too large for their mouths, comparing them to many lizards of the lip today.
"Some of today's monitor lizards have absolutely huge teeth," Cullen said. "It seems almost unbelievable that these teeth can be totally covered by lips and yet it is."
"And we found out that ... This scale ratio is almost identical for theropod dinosaurs."
What consequences for the representation of these famous predators in popular culture?
If Thomas Cullen acknowledges that the "Jurassic Park" movies managed "to stick to what was known" about dinosaurs "at the time", attempts to represent theropods in a "faithful" way have completely "derailed since", according to him.
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