SNOWBIRD, UTAH--The popular image of a Tyrannosaurus rex licking its snarling lips may have to be kissed goodbye. According to research presented here today at the annual meeting of the Society for Vertebrate Paleontology, the fearsome predator of the Cretaceous probably didn't have any chops whatsoever. But experts say that even without lips, T. rex would still have been an efficient killer.
Dinosaur reconstructions are often based on what "looks right," says Larry Witmer, a vertebrate paleontologist at Ohio University in Athens who specializes in the anatomy of dinosaur heads. Thus artists and sculptors have given T. rex thick muscular lips for smacking. Paleontologists have also thought that the vegetarian Triceratops sported muscular cheeks to aid in chewing, like sheep. To test these two assumptions, Witmer and his colleagues examined the carcasses of large mammals, as well as the closest living relatives of dinosaurs: birds and crocodiles.
First of all, Witmer points out, birds and crocodiles don't have lips. And when he dissected lizards--another relative of dinosaurs--he found that they had only thin lips with no muscles attached. "There's no justifiable scientific reason to put lips on dinosaurs," says Witmer. The muscular cheek theory didn't hold up either: None of the modern dinosaur ancestors have cheeks, he notes. And animals that do have muscular cheeks--like bison and cows--come equipped with bony ridges and small knobs to support them. By contrast triceratops had only a smooth shelf of bone above the teeth.
Other paleontologists aren't just paying lip service to the potential new look for the King of Predators. A lipless T. rex would still have been a fearsome hunter, says Greg Erickson of Stanford University. "It's the teeth that matter."