They probably did not smile, but T-Rex almost certainly had lips. This new finding challenges our ideas of these predators having big nasty teeth sticking out of their mouths.
Scientists studied three kinds of evidence: the skull and jaw anatomy of all the meat-eating dinosaurs, the wear patterns of their teeth, and the relationship between tooth size to skull size.
"Our study suggests that these dinosaurs did not have exposed teeth when their mouth was closed," says palaeontologist Thomas Cullen.
"Dinosaur lips would be different from mammal lips ... they could not be curled back into a snarl like lips in humans or other mammals," he says. "In this way, dinosaur lips would be more similar to those of many lizards."
