Non-avian theropod dinosaurs such as the iconic Tyrannosaurus rex have long been portrayed with their teeth fully visible, similar to living crocodiles. This pattern of portrayal largely had to do with relatedness between dinosaurs and crocodiles and the relationship between tooth and jaw size. In new research, paleontologists from Canada, China and the United States tested hypothesized facial reconstruction in this group using analysis of tooth wear patterns and quantitative relationships between skull length and tooth size in both extinct and living reptiles. Contrary to depictions that have dominated for more than a century, they found that theropods, including Tyrannosaurus rex, had lips that covered their teeth, leaving them looking more like modern Komodo dragons than crocodiles.
Non-avian theropod dinosaurs are renowned for their large, dagger-like teeth.
As a result, scientific and popular reconstructions of these dinosaurs have often featured these teeth as exposed, prominently protruding outside their closed mouths like crocodiles.
However, theropod teeth are known to have relatively thin enamel.
Since large theropod species likely retained their sharp and serrated teeth over long periods of time, it’s thought that constant exposure would likely lead to damaging tooth desiccation and wear.
Whether these ancient apex predators’ teeth were permanently exposed, as is often depicted, or covered by lip-like labial scales like a Komodo dragon, remains uncertain.
“Dinosaur artists have gone back and forth on lips since we started restoring dinosaurs during the 19th century, but lipless dinosaurs became more prominent in the 1980s and 1990s,” said Dr. Mark Witton, a paleontologist at the University of Portsmouth.
“They were then deeply rooted in popular culture through films and documentaries — Jurassic Park and its sequels, Walking with Dinosaurs and so on.”
“Curiously, there was never a dedicated study or discovery instigating this change…
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