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Predatory dinosaurs had lizard-like lips

A new study published in the journal Science has challenged the popular depiction of predatory dinosaurs, such as Tyrannosaurus rex, as having permanently exposed teeth like modern crocodiles. Instead, the experts have discovered that these dinosaurs had lips similar to those of lizards and their relatives, the tuatara, a rare species of reptile currently found only in New Zealand, which is the last survivor of an order of reptiles that thrived in the age of the dinosaurs.

The researchers examined the tooth structure, wear patterns, and jaw morphology of lipped and lipless reptile groups and found that theropod mouth anatomy and functionality resembles that of lizards more than crocodiles, implying the existence of lizard-like oral tissues, such as scaly lips covering their teeth.

“Dinosaur artists have gone back and forth on lips since we started restoring dinosaurs during the 19th century, but lipless dinosaurs became more prominent in the 1980s and 1990s. They were then deeply rooted in popular culture through films and documentaries — Jurassic Park and its sequels, Walking with Dinosaurs and so on,” said study co-author Mark Witton, an expert in Paleoecology at the University of Portsmouth

“Curiously, there was never a dedicated study or discovery instigating this change and, to a large extent, it probably reflected preference for a new, ferocious-looking aesthetic rather than a shift in scientific thinking. We’re upending this popular depiction by covering their teeth with lizard-like lips. This means a lot of our favorite dinosaur depictions are incorrect, including the iconic Jurassic Park T. rex.”

The investigation revealed that tooth wear in lipless animals was significantly different from that seen in carnivorous dinosaurs and that dinosaur teeth were no larger – relative to skull size – than those of modern lizards, suggesting that they were not too big to cover with lips. Moreover, the distribution of small holes around the jaws, which supply nerves and blood to the gums and tissues around the mouth, appeared to be more lizard-like than crocodile-like in dinosaurs.

“As any dentist will tell you, saliva is important for maintaining the health of your teeth. Teeth that are not covered by lips risk drying out and can be subject to more damage during feeding or fighting, as we see in crocodiles, but not in dinosaurs,” explained co-author Kirstin Brink, an assistant professor of Palaeontology at the University of Manitoba.

These findings provide new insights into how to reconstruct the soft-tissues and appearance of dinosaurs and other extinct species, offering important information on how they fed, how they maintained their dental health, and the broader patterns of their evolution and ecology.

“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. 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,” concluded lead author Thomas Cullen, an assistant professor of Paleobiology at Auburn University.

By Andrei Ionescu, Staff Writer

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