Not that you’d want to kiss them, but T. rex actually had lips.

AP News reports on research into the fearful mouth of the scariest of flesh-eating dinosaurs which found that – despite the public image of Tyrannosaurus rex as being a snaggle-toothed fang beast – the big fellas actually had faces more like today’s monitor lizards, with their teeth mostly invisible most of the time:

Some thought the predators’ teeth were just too big to fit in their mouths, said study author Thomas Cullen, a paleontologist at Auburn University in Alabama.

When researchers compared skulls from dinosaurs and living reptiles, though, they found this wasn’t the case. Some large monitor lizards actually have bigger teeth than T. rex compared to their skull size, and can still fit them under a set of scaly lips, Cullen said.

The scientists also found clues in the pattern of wear and tear on tooth surfaces.

For a creature like a crocodile, whose teeth stick out of its mouth, the exposed part gets worn down quickly — “like someone’s taken a sander to the side of the tooth,” said another study author Mark Witton, a paleoartist at England’s University of Portsmouth.

But when researchers analyzed a tooth from a Daspletosaurus, a T. rex relative, they found it was in good condition and it didn’t show that uneven damage pattern.

With this evidence and other clues from the dinosaurs’ anatomy, the study makes a good case for lipped tyrannosaurs, said University of Maryland paleontologist Thomas Holtz, who was not involved with the study. Still, “we’re not talking kissy lips,” he pointed out — they’d be thin and scaly like those of the Komodo dragon, a large lizard.

You can read the original research here, in Science.