The leathery Tyrannosaurus Rex of vintage imagination has given way to the feathered horror of modern paleontological speculation. But science has one more adjustment to make to our understanding of the ancient theropod: those enormous teeth were perhaps covered by weird scaly lips too.
Analyses of dental histology from crocodylians and theropod dinosaurs, including Tyrannosaurus rex, further indicate that the most likely condition was complete coverage of the marginal dentition with extraoral tissue when the mouth was closed. This changes our perceptions about the appearance and oral configuration of these iconic predators and has broad implications for our interpretations of other terrestrial animals with large teeth.
