Auburn professor’s research indicates dinosaurs had lips

International study contends theropods’ teeth were not visible when mouths were closed
FILE - Stan, one of the largest and most complete Tyrannosaurus rex fossil discovered, is on...
FILE - Stan, one of the largest and most complete Tyrannosaurus rex fossil discovered, is on display, Tuesday, Sept. 15, 2020, at Christie's in New York. The teeth on T. rex and other big theropods were likely covered by scaly lips, concludes a study published Thursday, March 30, 2023, in the journal Science. The dinosaur's teeth didn't stick out when its mouth was closed, and even in a wide open bite, you might just see the tips, the scientists found. (AP Photo/Mary Altaffer, File)(Mary Altaffer | AP)
Published: Apr. 1, 2023 at 10:55 AM CDT
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AUBURN, Ala. (WSFA) - Auburn University’s Thomas Cullen is part of an international collaboration of researchers that has uncovered evidence that contrary to popular belief, theropod dinosaurs like the Tyrannosaurus rex and Velociraptor had lips that covered their teeth.

Cullen, an assistant professor in the College of Sciences and Mathematics Department of Geosciences, and his colleagues published their findings on that contradicts the traditional view about the appearance of the exotic extinct animals.

Their research has many important implications for understanding the animal’s biology and evolution.

“We reconstructed soft tissue anatomy, compared dental measurements, and studied dental health and wear records to further uncover that what you are used to seeing on the big screen is not accurate,” Cullen said. “The teeth of these theropod dinosaurs did not experience wear and tear like a crocodile and most likely had a lip-like covering.”

The scientific findings may change how people see theropod dinosaurs and impact studies of their paleobiology. These animals possessing lips means that their teeth wore down and functioned differently, discoveries that could impact future biomechanical reconstructions. The presence of additional soft tissues also has implications for their feeding ecology and life history.

Overall, these new results create an invaluable framework that impacts dinosaur paleontology and studying the structure of ecosystems. Traditionally, animations and CGI of famous T. rex and Velociraptor dinosaurs in blockbuster movies like “Jurassic Park” have featured the animals with their teeth exposed and on display at all times.

However, this new research questions whether or not this popular representation is scientifically and historically correct. Cullen and the team of researchers do not feel so. They compared multiple aspects of the paleobiology of theropod dinosaurs, including:

  • Tooth wear- The amount of wear on the actual enamel and dentine of their teeth showed less wear than those of their closest living relatives, the crocodile.
  • Size and scale- The size of the skull in approximation to the jaw and teeth proves they could have had lips, and their teeth would not be too large to be covered.
  • Bone anatomy- The surface features of the bone around the teeth are much more similar to lizards than crocodiles, including possessing a line of small pits which house blood vessels and nerves for their oral skin and gums.

According to the researchers, the theropods’ lips were more similar to lizards and were not like the lips of mammals or humans.

“Dinosaur lips would be very different from our lips, in that although they would cover the teeth, they could not really be moved independently, couldn’t be curled back into a snarl, or make other sorts of movements we associate with lips in humans (or other mammals),” Cullen said. “In this way, dinosaur lips would be more similar to those of many lizards or amphibians, even if we typically associate the structure of lips with mammals like ourselves.”

The research team includes a wide range of experts, including (but not limited to) Cullen; Kirstin Brink, assistant professor, Department of Earth Sciences at the University of Manitoba; Mark P. Witton, University of Portsmouth; and Derek Larson, collections manager, Royal BC Museum. This project primarily represents a collaboration of former and current students of the two study senior authors. This group of researchers combined their expertise in anatomy, tooth histology, statistical analysis, and evolutionary biology to explore this theory.

For Cullen, many of the analyses were conducted while he was a post-doctoral student at the Field Museum of Natural History in Chicago, where he is now also a Scientific Affiliate. Measurements taken from the museum’s famous skeleton of “SUE” the T. rex played an essential part in unraveling the mystery.

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