Tyrannosaurus rex may have scaly lips that cover the teeth.
The researchers say the description of a predator with huge shiny teeth, which is perfectly visible, may be incorrect.
In a study published Thursday in the journal Science, paleontologists compared skulls to living reptiles.
Their discovery distorted the image of the classic "Jurassic Park" series, finding that the teeth of Tyrannosaurus rex and other large theropods may have covered the lips. When its mouth is closed, its teeth do not stick out, and even if it opens its mouth, it can only see its lips.
This illustration was written by Mark M. Courtesy of P. Wyton in March 2023, it depicts a juvenile Edmontosaurus being eaten by a Tyrannosaurus rex with a lip. The teeth of Tyrannosaurus rex and other large theropods may have been covered with scaly lips, concluded a study published Thursday, March 30, 2023 in the journal Science. Scientists have found that dinosaur teeth don't stick out when the dinosaur's mouth is closed, and even in a wide open bite, you may only see the tip.
Some large monitor lizards actually have larger teeth than the size of the skull of Tyrannosaurus rex, and can still place them under a set of scaly lips, according to study author Thomas Karen, a paleontologist and assistant professor at Auburn University.
"We reconstructed soft tissue anatomy, compared dental measurements, looked at dental health and wear records to further discover that what you're used to seeing on the big screen isn't accurate," he said in a press release from the university. "The teeth of these theropod dinosaurs were not as worn as crocodiles and most likely had a labial covering.
Examination of the wear of the teeth also points to these conclusions.
An analysis of the tooth of Tyrannosaurus rex's relative, Daspletosaurus, found that it was in good condition and did not show an uneven pattern of damage — something that manifests itself in organisms with teeth sticking out of the mouth.
"This changes our perception of the appearance and oral configuration of these iconic predators and has wide-ranging implications for our interpretation of other terrestrial animals with large teeth," the authors said.
David Hanke, an official in the exhibition department at the Field Museum in Chicago, put the finishing touches on the skull of SUE, the world's largest Tyrannosaurus rex, which was exhibited at the 2005 Dinosaur Expo at the National Museum of Nature and Nature in Tokyo on March 14, 2005.
Auburn said measurements taken from the skeleton of the "SUE" Tyrannosaurus rex at the Field Museum of Natural History in Chicago played an important role in the study.
The museum says SUE is the largest and most complete specimen of Tyrannosaurus rex found, accounting for about 90 percent.
The study, the latest in a long iteration of what dinosaurs' mouths really look like, is not the first time that descriptions of Tyrannosaurus rex and dinosaurs have been questioned.
On Tuesday, April 1, 2014, visitors to the Field Museum of Natural History in Chicago admired SUE, one of the largest, most extensive, and best-preserved specimens of Tyrannosaurus rex ever discovered.
For example, other studies have shown that Tyrannosaurus rex was more hunchbacked than initially thought, and that velociraptors may have feathers.
Much of what we know about dinosaurs comes from their skeletons, but it may be harder to get definitive answers about soft tissues like skin, which are not usually preserved as fossils.
Cullen noted that dinosaur lips "are very different from ours in that while they cover the teeth, they can't really move independently, can't curl into growls, and can't make other types of movements, and we're related to the lips of humans (or other mammals)."
"In this way, the lips of dinosaurs would be more similar to those of many lizards or amphibians, even though we usually associate the structure of the lips with mammals like us," he explains.