New Study Challenges Long-Held Belief: Did T-Rex Really Have Exposed Teeth?

A new study published in Science on March 30 challenges the long-held belief that large theropod dinosaurs, including the iconic Tyrannosaurus rex, had exposed teeth when their mouths were closed. According to the study, it appears that their teeth were shielded by slender, scaly lips akin to those of contemporary Komodo dragons. The discoveries made could have an effect on how we comprehend the dental anatomy, feeding habits, biomechanics, and depiction of dinosaurs in both scientific and mainstream culture.[0]

For more than a century, dinosaurs of the Theropoda clade, such as the Tyrannosaurus rex, have been depicted with fully visible teeth, but new research has shown that these creatures actually had lizard-like lips that fully covered the teeth. Additionally, the scientists noted that the dinosaurs possessed lips resembling not only those of lizards and crocodiles, but also their distant relative, the tuatara. This reptile is exclusively found in New Zealand, which is also home to the only surviving members of an order of reptiles that flourished during the dinosaur era.[1] According to them, the dinosaurs did not possess muscular lips like mammals.[2]

According to the study's co-author, Thomas Cullen, a professor at Auburn University, the lips of dinosaurs would have been distinct from ours. Despite covering their teeth, they would not have been capable of independent movement, such as curling into a snarl or performing other actions commonly associated with human lips. Despite our tendency to associate lip structure with mammals like ourselves, dinosaur lips were likely more similar to those of lizards or amphibians.

After analyzing the teeth, wear patterns, and jaw shape of reptiles with lips and without lips, the researchers discovered that the way theropods use their mouths is more similar to lizards than crocodiles.[3] According to the study, lipless creatures like crocodiles exhibit significant wear and abrasion on their uncovered teeth.[4] The absence of significant harm on the periphery of the carnivorous dinosaurs suggests that their teeth remained concealed.[4] According to the study, the perforations present around the jaws that provide sensory pathways and blood vessels to the gums are more similar to lizards in dinosaurs than in crocodiles.[4]

It is a known fact that the enamel on theropod teeth is comparatively thin.[5] It is believed that continual exposure could lead to harmful drying and erosion of teeth, as giant theropod species probably maintained their sharp, saw-toothed teeth for long periods of time. Nevertheless, the enamel on theropod teeth is comparatively thin. It is believed that continuous exposure to their sharp and serrated teeth caused damaging desiccation and wear over extended periods of time for the large theropod species. It is unclear whether the teeth of these prehistoric top predators were always visible, as commonly shown, or concealed by scale-like lips similar to those of a Komodo dragon.

One part of the research looked at tooth damage.[6] The teeth that are visible are more worn out compared to the ones hidden behind the lips. Crocodylians, for instance, have noticeably abraded external teeth.[6] But when the researchers examined theropod teeth using microscopes and compared them with crocodylian teeth, they found that theropod teeth were considerably less damaged.

Although some extinct animals such as saber-toothed carnivorous mammals or marine and flying reptiles with long, interlocking teeth may have had exposed teeth, the researchers clarify that their study does not suggest that no extinct animals possessed this feature. The researchers emphasized that the absence of visible teeth in theropod dinosaurs does not imply that other extinct creatures lacked them. They pointed out that carnivorous mammals with saber-like teeth did possess them.

“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,” University of Portsmouth researcher Mark Witton said in a news release.[7] The researchers posited that these labial scales would have protected theropods’ serrated teeth over the course of their lives, preventing the dentition from wearing down. The researchers found that the theropod teeth they examined did not exhibit any indications of wear caused by exposure and dehydration.[8]

0. “Deadly Teeth of T. rex Were Hidden Behind Scaly Lips, Shattering Prehistoric Perceptions” SciTechDaily, 30 Mar. 2023,

1. “Pucker up! Study states that dinos such as T. rex had lizard-like lips” The Jerusalem Post, 31 Mar. 2023,

2. “Scaly lips may have hidden the T-rex’s fearsome teeth” Popular Science, 30 Mar. 2023,

3. “Tyrannosaurus rex had lips over its teeth, research suggests” The Guardian, 30 Mar. 2023,

4. “Tyrannosaurus rex had lips, says new research – Victoria Times Colonist” Times Colonist, 30 Mar. 2023,

5. “T-Rex smile: Infamous dinosaur may have had “lizard-like lips” | Canada” Daily Hive, 30 Mar. 2023,

6. “Tyrannosaurus rex: our new research shows it covered its enormous teeth with lips” The Conversation, 31 Mar. 2023,

7. “The Tyrannosaurus rex may not have shown big teeth after all” Scripps News, 31 Mar. 2023,

8. “Theropods Like T. Rex Had Lips, Study Finds” Gizmodo, 30 Mar. 2023,

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