The Tyrannosaurus usually depicted with his fearsome teeth on full screen. But a paper published in Science states that theropod dinosaurs, such as T-Rexin fact, it had thin, lizard-like lips that hid their sharp, jagged teeth.
Tyrannosaurus rex roared with its mouth closed like a vocalizing alligator. With its mouth closed, all of the T. rex’s enormous teeth would be invisible behind its lips. (Credit: Mark Wheaton)
Theropod teeth
Paleontologists and paleoartists tasked with depicting dinosaurs have long debated the appearance of theropods. While some suggest that these carnivorous dinosaurs had lizard-like lips that covered and concealed their teeth, others suggest that they lacked lips, exposing their teeth in a terrifying snarl with snapping teeth.
“Dinosaur artists moved back and forth on their lips,” said study author Mark Wheaton, a paleontologist and paleoartist affiliated with the University of Portsmouth, according to press release. “But the mouthless dinosaurs became more famous in the 1980s and 1990s. Then they were deeply embedded in popular culture through movies and documentaries.
That being said, the scientific basis behind these popular images was weak.
“Curiously, there has never been a specific study or discovery that has caused this change,” Wheaton said in a release. “To a large extent, this probably reflects a preference for a new, ferocious-looking aesthetic rather than a change in scientific thinking.”
Read more: This is what dinosaurs really looked like
With or without lips
Now researchers have analyzed the theropod teeth in more depth, along with the teeth of their more modern reptilian relatives, finding that the ancient animals had scaly, soft tissues around their teeth.
“We pay attention to this popular image by covering their teeth with lizard-like lips,” says Whitten. “This means that many of our favorite images of dinosaurs are incorrect, including the iconic Jurassic Park.” T. Rex.
Reconstructions of the T. rex skull and head (Photo: Mark Wheaton)
Overall, the researchers say their paper provides important information about the diet and dental fitness of these dinosaurs. It also demonstrates the value of a new approach to reconstructing the appearance of all kinds of ancient animals, including other dinosaurs.
“Some believe we have no idea what dinosaurs looked like beyond basic characteristics like the number of fingers and toes,” Whitten says. “But our study and others like it show that we have an increasingly good handle on many aspects of dinosaur appearance.”
Read more: What the Tyrannosaurus rex skull tells us about its intelligence
Study Dinosaur Smackers
To arrive at these findings, the researchers compared the morphology of the teeth and mouths of theropods to those of modern reptiles, with and without lips. Their comparisons reveal that theropod mouths are much more similar to those of lipped reptiles, such as lizards, than to lipless reptiles, such as crocodiles.
Of particular importance to their conclusions are tooth wear and size. While the wear seen in theropods is very different from that seen in lipless reptiles, the tooth size of theropods is very similar to that of oral reptiles, relative to the size of their skulls.
“Although it has been argued in the past that the teeth of carnivorous dinosaurs may have been too large to be covered by lips, our study shows that in fact their teeth were not atypically large,” said study author Thomas Cullen, paleontologist , affiliated with Auburn University, according to a press release. “Even the giant teeth of tyrannosaurs are proportionally similar in size to those of living carnivorous lizards compared to the size of the skull, rejecting the idea that their teeth were too large to cover lips.”
According to the researchers, the theropod’s lips protect their teeth from excessive exposure to the environment, reducing the amount of damage their enamel sustains during feeding. And since most modern lizards are unable to move their lips on their own, the researchers also add that theropod lips were not muscular, most closely resembling those of monitor lizards.
“It’s remarkable how similar the teeth of theropods are to those of lizards. From the smallest monitor to the Komodo dragon, teeth function in much the same way,” said study author Derek Larson, a paleontologist associated with the Royal BC Museum in Canada, according to a press release“although not closely related”.
Ultimately, the researchers stress that their study only applies to theropods and theropods. So while some dinosaurs undoubtedly showed their teeth, Tyrannosaurus was not one of them.
Read more: T. Rex developed differently shaped eye sockets for a strong bite