April 4, 2023 | David F. Coppedge

Gummy Rex Did Lip Service

Jurassic Park was wrong, says a new rethink about dinosaur lips.
T. rex probably didn’t bare its teeth most of the time.


Every child’s favorite dinosaur is getting a face lift. Instead of the snarling, screaming mouth full of bared teeth seen in most movies, T. rex‘s mouth had lips, some scientists now say. Whether it kissed its mate or not is too hard to say without living ones to observe, but that idea would have made good fodder for comics. “My, what big lips you have, grandma.” “The better to kiss you with, child.”

Holding those big teeth in place, the scientists also argue, would have required big gums. The Gummy Bears candy makers could have fun with a new line of Gummy Rex treats.

At The Conversation, co-author of the paper in Science Mark P. Witton of the University of Portsmouth shares some of the lines of evidence in T. rex bones and teeth that led him and his colleagues to their revision of the monster’s makeup.

  • Wear and tear: Tooth wear matched lizards more than bared-tooth crocodiles.
  • Holes in the jaw for blood vessels matched lizards more than crocodiles.
  • Without lips, a theropod’s mouth would have dried out because it could not form a seal.
  • Tooth size was proportionally the same as with lizards, which have lips.

Our comparisons revealed that no predatory dinosaurs – even the big-toothed T. rex – had teeth larger than living lizards. Indeed, species like the crocodile monitor have proportionally larger teeth than any theropod, so there’s no reason to think dinosaur teeth were too big to be covered by lips.

Sorry, Hollywood. There’s a new lippy look for theropods (artwork provided by Mark Witton in the press release).

Predatory dinosaurs such as T. rex sported lizard-like lips (University of Portsmouth press release, 30 March 2023). The press releases emphasizes that scientists have been wrong for decades if this facelift is correct.

The study challenges some of the best-known depictions of predatory dinosaurs and suggests that even the giant teeth of Tyrannosaurus rex would have been covered in scaly, lizard-like lips.

Given how popular T. rex is to the public, it’s astonishing that this was never deduced before. Mark Witton hints that Hollywood liked the fierce look of bare teeth:

There was never a dedicated study or discovery instigating this change and, to a large extent, it probably reflected preference for a new, ferocious-looking aesthetic rather than a shift in scientific thinking. We’re upending this popular depiction by covering their teeth with lizard-like lips. This means a lot of our favourite dinosaur depictions are incorrect, including the iconic Jurassic Park T. rex.

The press release points out that the rethink about dino lips does not mean that all extinct toothy beasts had them. It would be difficult to imagine lips on a sabre-tooth cat, for instance.

Tyrannosaur at the Wyoming Dinosaur Center. Photo by David Coppedge.

Those protruding T Rex teeth? They were covered by lips: study (Phys.org, 2 April 2023). Lips on T. rex? Reporter Chris Lefkow grins, “It’s not an open and shut case, but that’s the conclusion of a team of international researchers whose findings are published Thursday in the journal Science.”

T. rex had thin lips and a gummy smile, controversial study suggests (Live Science, 30 March 2023). Calling the study “controversial,” reporter Sascha Pare seems to want to keep the possibility open that the Jurassic Park look was the correct one. Some are not ready to “lip off” a dinosaur.

Some paleontologists remain convinced that theropod dinosaurs sported the lipless look that their crocodile descendants have today. “The authors make claims about tyrannosaur teeth that don’t map onto the fossils I’ve seen,” Thomas Carr, an associate professor at Carthage College in Wisconsin, and lead author of a 2017 study on tyrannosaur lips published in the journal Scientific Reports, told Live Science in an email.

Facelift for T. rex: analysis suggests teeth were covered by thin lips (Nature News, 30 March 2023). This article examines the evidence that lipped T. rex faces made these “gummy dragons” look “less monstrous and more natural.” Not everyone is ready. How to prove it? Soichiro Kawabe, a vertebrate palaeontologist in Japan, weighs in:

“I doubt it will be the final word in this contentious debate,” he says. “Ultimately, we need to find a fossil T. rex mummy with skin and muscles and scales still preserved on the head,” he says. “That would tell us once and for all whether there were lippy tissues covering the teeth, or whether the teeth were more exposed.”

Is it possible to find soft tissue evidence like that on a dinosaur? See announcement in the comments below.

Young live tuatara in terrarium at the Otorohanga Bird Sanctuary, NZ (DFC). Note the lips on this dinosaur-era “living fossil.”

Cullen et al., Theropod dinosaur facial reconstruction and the importance of soft tissues in paleobiology (Science, 30 March 2023). This is the scientific paper where the authors make their arguments for lips on dinosaurs – not just on T. rex, but probably on all the smaller theropods, too. Note: varanids are monitor lizards like the Komodo Dragon of Java. They have lips and closed mouths like most lizards.

Given the close fit of multiple lineages of small theropods to the tooth-to-skull size relationship documented in varanids, well-developed extraoral tissues appear likely in smaller members of all major theropod groups, and it is unlikely for tooth height to have exceeded facial soft tissue growth, even in larger theropods.

But could lips evolve on some dinosaurs after being separated from the lizard line for a hundred million years? No problem, think these Darwinians. Anything can happen with the Stuff Happens Law, even fleshy lips, complete with blood vessels and specialized cells, made just big enough to fit the big teeth of a T. rex. They think the monsters could not have moved their lips into a snarl, but without evidence, how do they know the lips lacked muscles? Are they underestimating the creative power of the Stuff Happens Law?

Note: lepidosaurs are reptiles that include snake snakes, lizards, and rhynchocephalians like New Zealand’s tuatara.

Finally, we posit a lepidosaur-like plesiomorphic [i.e., primitive] condition for extraoral tissues in Dinosauria and expect that our results not only will provide a deeper understanding of the evolution of buccal soft tissues generally and advanced oral processing in ornithischians in particular but also, more broadly, will open new directions of research into the relationships between oral soft tissues and feeding behavior in terrestrial vertebrates with large teeth.

And so, waving the banner of the glories of futureware to come, they give lip service to the power of evolution to provide the coveted prize: “deeper understanding.”

The artwork is still wrong. The artist forgot to put imaginary feathers on the lips.

Theropods are the lineage of dinosaurs that supposedly evolved into birds. Interesting that theropods are said now to not only have lizard hips, but lizard lips, too. Theropods are “saurischians” (lizard-hipped) dinosaurs. The ones like Ankylosaurus and Tricerators that had “bird hips” (ornithischians) are not said by evolutionists to be related to birds and don’t look at all like birds. How many lucky mutations did it take natural selection to blindly innovate genes for lips on lizards originally, and to maintain them for millions of years in the saurischian lineage but not on the ornithischian lineage? Darwin works in mysterious ways.

Could soft tissue from lips be found on a dinosaur? On April 12 at 9:00 pm EDT, Dr Brian Thomas of ICR will be showcasing dozens of examples of soft tissue remains on fossils, some of them from dinosaurs. Click here to register for the live stream broadcast, sponsored by Logos Research Associates. (If you had signed up for our Newsletter, you would have heard about this last Sunday.)

Nice kitty. T rex model (ICR Creation Discovery Center). Need to add lips now?


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