Den­tal dis­crep­ancy in de­pict­ing di­nosaurs

Wouldn’t have had bared teeth, pro­fes­sor says

SundayXtra - - LIFE / SCIENCE - By Paola Lorig­gio

TORONTO — 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 con­trary to what’s shown in movies and even mu­se­ums, T. Rex and his fel­low theropods would not have had teeth that stick out even when their mouths were closed.

His re­search was pre­sented Fri­day at the Cana­dian So­ci­ety of Ver­te­brate Pa­le­on­tol­ogy con­fer­ence held at the uni­ver­sity’s Mis­sis­sauga cam­pus.

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

Part of that is be­cause “It makes the an­i­mals look more fierce,” Brown said.

But it’s also be­cause for some di­nosaurs, the teeth are the part pa­le­on­tol­o­gists know best be­cause more are avail­able, and it seems coun­ter­in­tu­itive to hide them in dis­plays, he said. If it turns out 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, Brown 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 years ago and plans to turn his pre­sen­ta­tion into a pa­per to be sub­mit­ted for peer re­view.

DAN PELLE / SPOKESMAN- RE­VIEW (COEUR D’ALENE) FILES

Chil­dren at an in­ter­ac­tive di­nosaur ex­hibit. The T. Rex is de­picted bar­ing sharp teeth, but a re­searcher says the teeth were likely cov­ered by lips.

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