One of the world's most famous predators, the fearsome Tyrannosaurus rex is typically shown baring dozens of sharp, jagged teeth — but a Toronto researcher says the carnivore likely had lips to cover them.

Robert Reisz, a professor at the University of Toronto who specializes in vertebrate paleontology, says that contrary to what's shown in movies and even museums, T. rex and his fellow theropods would not have teeth that stick out even when their mouths are closed.

His research is set to be presented Friday at a conference of the Canadian Society of Vertebrate Paleontology conference, held at the university's Mississauga campus. The two-day conference begins Thursday.

Reisz says only a few land animals, such as elephants and wild boars, have exposed teeth and these have no enamel.

Meanwhile, the only animal with bared teeth that have enamel is the crocodile, which is aquatic.

Reisz says theropods, which include other well-known dinosaurs such as velociraptors and Albertosaurus, were land animals whose teeth had enamel, making it far more likely they had lips.

"The available evidence would suggest that none of these animals — none of the theropod dinosaurs — should have their teeth sticking out of their mouths. They look more ferocious that way but that's probably not real," he said.

Though more work needs to be done to reconstruct what the ancient creatures would have looked like, "all the evidence right now points to the likelihood that they actually had their teeth covered by essentially scaly lips," he said.

In reconstructing what dinosaurs looked like, scientists rely on preserved anatomy -- typically bones, but sometimes skin and feathers -- and comparisons with modern animals, said Caleb Brown, a paleontologist working at the Royal Tyrrell Museum in Drumheller, Alta.

"And then a lot of it is artistic licence," said Brown, who has not seen Reisz's research.

"You have to estimate somewhere. One of the big ones we don't know about is colour. We're getting some details about colour from feathered dinosaurs but when we just have skin preserved we don't know what colour they are."

Whether or not theropods had lips has yet to be determined, and that debate plays out in popular culture as well as scientific circles, he said.

"It's kind of an ongoing joke in that when you draw a dinosaur, particularly a theropod, one of the meat-eating dinosaurs, you always portray it with the mouth open and with these teeth being shown," he said.

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Part of that is because "it makes the animals look more fierce," he said.

But it's also because for some dinosaurs, the teeth are the part that paleontologists know best, since more are available, and it seems counterintuitive to hide them in displays, he said.

If if turns out that theropods did have lips, there would be scientific implications for how they chewed and processed food, Brown said.

Still, "the biggest change that you would see would be in how these are portrayed to the public in what we call paleo art, or artists' reconstructions of these animals," which then trickles down to movies and museum exhibits, he said.

Reisz said the popular depiction in movies such as the "Jurassic Park" franchise has annoyed him "for a very long time because there is no real biology behind it."

Aside from their lack of lips, theropods are shown in movies without feathers and "looking emaciated," which he said is also incorrect.

Though the issue has been a longtime frustration, Reisz said he began researching it a year ago and plans to turn his presentation into a paper to be submitted for peer review.