T-rexes discovered to look completely different to how they've been pictured all this time

The T-rex may not have had the huge, razor-sharp protruding teeth that we’ve seen in films like Jurassic Park, according to a new study led by the University of Portsmouth.

Yep, we’ve all got a picture in our heads about the infamously fearsome Tyrannosaurus rex, but researchers behind a new paper believe their mouth structure actually resembled a tuatara, an extant reptile found in New Zealand that has descended from dinosaurs.

In the study – titled ‘Theropod dinosaur facial reconstruction and the importance of soft tissues in paleobiology’ and published this week in the journal Science – the international team of authors explained how large therapod dinosaurs are often depicted with ‘marginal dentition exposed because of the enormous size of their teeth and their phylogenetic association to crocodylians’.

Dr Mark Witton/University of Portsmouth

They decided to test this hypothesis, with regressions of skull length and tooth size for a range of creatures confirming that ‘complete coverage of theropod dinosaur teeth with extraoral tissues (gingiva and labial scales) is both plausible and consistent with patterns observed in living ziphodont amniotes’.

Analysis of dental histology from animals, including the T-rex, also indicated that the ‘most likely condition was complete coverage of the marginal dentition with extraoral tissue when the mouth was closed’.

Study leader Thomas Cullen, assistant professor of paleobiology at Auburn University in Alabama, said: “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.”

Dr Mark Witton/University of Portsmouth

Co-author Dr Mark Witton, from the University of Portsmouth in England, added: “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.

“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 favourite dinosaur depictions are incorrect, including the iconic Jurassic Park T. rex.”

Derek Larson, study co-author and Collections Manager and Researcher in Palaeontology at the Royal BC Museum in Canada, said it was ‘quite remarkable’ how similar theropod teeth are to monitor lizards.

He explained that the teeth function in the same way, meaning monitors can be compared ‘quite favorably with extinct animals like theropod dinosaurs based on this similarity of function, even though they are not closely related’.