Tyrannosaurus Rex Probably Had Giant, Full Gums and Lips That Covered Its Ferocious Teeth

If your childhood was ruined when you learned your favorite dinosaur actually had a fluffy coating of feathers, get ready for another blow. A new study suggests Tyrannosaurus rex had giant, full gums and lips that covered much of their teeth — far different from the gnashing jaws we saw in Jurassic Park.

"In popular culture, we imagine dinosaurs as more ferocious-looking, but that is not the case," paleontologist Robert Reisz said in a news release.

Why lips? Reisz developed this hypothesis by studying dental anatomy and living relatives of dinosaurs.

Lips protect teeth from drying out and they help preserve the enamel. Since dinosaur teeth are often found with well-preserved enamel, Reisz concluded that dinosaurs likely had a protective set of lips to hydrate the gums.

Reisz also examined the gums, teeth and lips of modern-day dinosaur relatives like crocodiles and monitors. Crocodiles have more exposed teeth, while monitors have a set of scaled lips. Since crocodiles spend most of their time in the water, they don't need lips for hydration or protection. But monitors, which spend most of their time on land, do.

Since T. rex and other theropods (a group of land-dwelling, carnivorous dinosaurs) spent most of their time on land, they probably had lips too. So, nope — probably not the toothy, terrifying beasts most people picture.