Pucker up! T. rex, other predatory dinosaurs lizard-like lips - study

Dinosaurs of the Theropoda clade, such as the Tyrannosaurus rex, have been depicted for more than a century with fully visible teeth, but new research has shown that these creatures actually had lizard-like lips that fully covered the teeth.

The paleontological study, published in the peer-reviewed journal Science, stated that this discovery of their appearance has "them looking more like modern Komodo dragons than crocodiles."

This study also applies to other theropod dinosaurs such as the velociraptor.

For the study, an international team of researchers tested hypothesized facial reconstruction of the tooth and jaw size of both dinosaurs and crocodilians. They did so by analyzing the tooth wear patterns and quantitative relationships regarding both extinct and extant reptiles' tooth size and the length of their skulls. Therefore, the research changes the perception of the ancient predators' appearance and may have "broad implications for our interpretations of other terrestrial animals with large teeth," the study states.

“It’s quite remarkable how similar theropod teeth are to monitor lizards. From the smallest dwarf monitor to the Komodo dragon, the teeth function in much the same way," said Derek Larson, co-author of the study and the Collections Manager and Researcher in Paleontology at the Royal BC Museum in Canada.

“Paleontologists often like to compare extinct animals to their closest living relatives, but in the case of dinosaurs, their closest relatives have been evolutionarily distinct for hundreds of millions of years and today are incredibly specialized."

Similarities to other species

The researchers also stated that these dinosaurs had lips similar to not just lizards and crocodiles, but to their relative, the tuatara, a reptile found only in New Zealand, which also conveniently happens to be the location of the last survivors of an order of reptiles that thrived in the age of the dinosaurs. They also state that the dinosaurs' lips were not muscular like in mammals.

“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 co-author Dr. Mark Witton from the University of Portsmouth. "We're upending this popular depiction by covering their teeth with lizard-like lips. This means a lot of our favorite dinosaur depictions are incorrect, including the iconic Jurassic Park T. rex.”

The researchers stressed that just because theropod dinosaurs didn't have exposed teeth, doesn't mean that other extinct animals didn't either, stating that saber-toothed carnivorous mammals did.