The real mouth of the Tyrannosaurus

A new study on the anatomy of the head of the Tyrannosaurus rex (Tyrannosaurus rex) contradicts more than a century of graphic representations, both popular and scientific.

Non-avian theropod dinosaurs are famous for their large, dagger-shaped teeth. As a result, popular and scientific reconstructions of these dinosaurs have often portrayed these teeth as exposed, protruding prominently out of their closed mouths as in crocodiles, rather than covered by soft facial tissues of the mouth as in the mouth. most other land reptiles, such as today’s Komodo dragons.

However, theropod teeth are known to have relatively thin enamel. Since large theropod species probably retained their sharp, serrated teeth for long periods of time, it has been believed that constant exposure must lead to desiccation and wear of the teeth.

It has long been unclear whether the teeth of these ancient predators were permanently exposed, as they are often depicted, or covered by labial scales as in the case of the Komodo dragon.

In order to test alternative hypotheses of theropod facial reconstructions, the team of Thomas Cullen of Auburn University in the United States and Mark Witton of the University of Portsmouth in the United Kingdom evaluated the relationship between skull length and tooth size for various living and extinct theropod dinosaurs and toothed reptiles.

The researchers performed a comparative histological analysis of tooth wear patterns for tyrannosaurid and crocodilian teeth.

According to Cullen and his colleagues, unlike their closest toothed crocodilian relatives, theropods had teeth that lacked evidence of external surface wear, indicating the existence of extraoral tissues and oral secretions necessary to keep them hydrated and protected. in front of the exhibition.

Furthermore, the study authors found that despite the skulls and teeth of some theropods being much larger than those of extant reptiles, the relationship between skull-to-tooth size in theropods was closely aligned with that of theropods. living reptiles, particularly monitor lizards, which do not have exposed teeth.

These findings suggest that theropod teeth were not too large to fit in their mouths without being exposed. Cullen and his colleagues argue that the data suggests that all theropod dinosaurs had teeth completely covered by labial scales when the mouth was closed.

An artist’s rendering of what a typical Tyrannosaurus rex would have looked like in life, based on what was discovered in the new study. With his mouth closed, his terrifying teeth would be hidden behind his lips. (Image: Mark Witton)

The findings could have important implications for understanding dinosaur dental anatomy, feeding ecology, and the biomechanics of their eating actions, as well as for the graphic representation of dinosaurs in science and popular culture.

The study is titled “Theropod dinosaur facial reconstruction and the importance of soft tissues in paleobiology”. And it has been published in the academic journal Science. (Source: AAAS)