Dinosaurs such as Tyrannosaurus rex have been wrongly shown in films such as Jurassic Park to have “ferocious-looking” exposed teeth, according to new research.
Scientists have instead found that many predatory species would have had scaly, lizard-like lips covering and sealing their mouths.
Theropod dinosaurs, a group of two-legged dinosaurs which includes the velociraptor as well as birds, were previously thought to have lipless mouths where visible upper teeth hung over their lower jaws, similar to the mouth of a crocodile.
The scientists 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.
They said this implies lizard-like oral tissues, including scaly lips covering the teeth.
The researchers said these lips were probably not muscular, like they are in mammals, as most reptile lips cover their teeth but cannot be moved independently or curled back into a snarl.
Co-author Dr Mark Witton, from the University of Portsmouth, said: “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.
“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.”
The results, published in the journal Science, found that dinosaur teeth were no larger, relative to skull size, than those of modern lizards, suggesting they were not too big to be covered with lips.