Tyrannosaurs had lips similar to those of lizards. Reported by the University of Portsmouth.
Researchers and artists debate whether theropod dinosaurs, which include top carnivores like Tyrannosaurus Rex and Velociraptor, had lipless mouths. In the absence of lips, the upper teeth should hang over the lower jaws, similar to the layout of the mouth in modern crocodiles. At the same time, it is very difficult to learn about fossil animals – soft tissues, especially those without a pronounced structure, such as lips, are poorly preserved in the fossil record.
In this regard, Derek Larson and his colleagues conducted extensive study of paleontological remains to find out how the mouths of dinosaurs were arranged. The authors examined the structure of the teeth, wear patterns, and morphology of the jaws of “liped” and labile reptile groups and found that the anatomy and functionality of theropod mouths were more similar to those of lizards than of crocodiles. It turns out that dinosaurs had lizard-like oral tissues, including scaly lips that covered their teeth.
“It’s amazing that theropod teeth are similar to those of monitor lizards. From the smallest dwarf monitor to the giant Komodo dragon, teeth work pretty much the same. Thus, monitor lizards, even if not closely related, are aptly compared to extinct animals such as theropod dinosaurs based on similarities in jaw function, ‘ explain the authors.
To these conclusions not only the nature of the wear of the teeth, but also their size – they were small enough to hide under the lips. Also, the arrangement of tiny openings in the jaws that supply nerves and blood to the gums and tissues around the mouth was more characteristic of dinosaurs than of crocodiles. Finally, mouth closure simulations with lipless theropod jaws showed that the jawbone had to either crush the bones supporting the jaw or tear off the jaw joint to close the mouth.