4. Natural History Museum
A full-scale model of tyrannosaurus rex at the Natural History Museum in LondonReuters

Carnivorous dinosaurs such as tyrannosaurus rex and velociraptor had lips and gums covering their large teeth, making them appear far less ferocious than traditional depictions, a palaeontologist has argued. Robert Reisz, from the University of Toronto, compared portrayals of theropods to modern-day crocodiles and lizards to better understand what these extinct predators would have looked like.

"When we see dinosaurs in popular culture, such as in the movie Jurassic Park, we see them depicted with big teeth sticking out of their mouths," he said. While T-Rex is normally shown with massive teeth sticking out of its mouth, velociraptors are shown with scaly lips.

Despite huge amounts of fossil evidence, we have a fairly poor understanding of what dinosaurs looked like. Last year, researchers announced they had potentially worked out how to tell what colour their skin would have been through skin pigments. Furthermore, researchers are increasingly finding many species had feathers – a far step from historical depictions.

To gain an insight into theropod mouths, Reisz looked at water-dwelling crocodiles, which have exposed teeth, and land-bound monitor lizards. Lips help protect teeth by providing an enclosed moist environment. Because crocodiles spend their lives in water, they do not need lips for protection. "Their teeth are kept hydrated by an aquatic environment," Reisz explained. However, lizards do have lips to protect their teeth.

Presenting his findings at the annual meeting of the Canadian Society of Vertebrate Paleontology, Reisz says this means theropod dinosaurs (which lived on the land) would probably have had scaly lips covering their teeth.

"It's also important to remember that teeth would have been partially covered by gums," he said. "If we look at where the enamel stops, we can see that a substantial portion of the teeth would be hidden in the gums. The teeth would have appeared much smaller on a living animal. In popular culture, we imagine dinosaurs as more ferocious-looking, but that is not the case."