How Did The T-Rex Chew Bones Of Prey With Such Ease? 3D Model Reveals Super Stiff Skull

COLUMBIA, Mo. — No dinosaur movie, book, or theme park ride would be complete without an appearance by the most recognizable and fearsome dinosaur of all, the tyrannosaurus rex. Thanks to its immense size and terrifying appearance the T-rex has captured the imaginations of millions and is synonymous with modern depictions of dinosaurs. This monstrous dinosaur was capable of shattering the bones of its prey in a single bite without harming itself or breaking its own skull bones, an ability that had always confused paleontologists — up until now.

Using a new 3D model of a T-rex skull’s ligaments and joints, scientists from the University of Missouri-Columbia have concluded that the T-rex likely had an extremely stiff skull, similar to that of a crocodile or hyena. Previously, paleontologists had asserted that the T-Rex’s skull was more flexible, like snakes and birds.

T-Rex jaw 3D image
A 3D image of a Tyrannosaurus rex skull showing muscle activation. University of Missouri scientists created one of the first 3D models showing how ligaments and joints in the skull of a Tyrannosaurus rex work. (Image credit: University of Missouri)

“The T. rex had a skull that’s 6 feet long, 5 feet wide and 4 feet high, and bites with the force of about 6 tons,” says Kaleb Sellers, a graduate student in the MU School of Medicine, in a release. “Previous researchers looked at this from a bone-only perspective without taking into account all of the connections — ligaments and cartilage — that really mediate the interactions between the bones.”

The research team utilized a combination of engineering analysis, imaging, and anatomy to recreate how the roof of a T-rex’s mouth dealt with the unbelievable amount of stress and strain that would result from eating other dinosaurs whole. An integral part of this process was applying the chewing movements of parrots and geckos, two of the T-rex’s modern day relatives, to how the T-rex skull worked.

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“Dinosaurs are like modern-day birds, crocodiles and lizards in that they inherited particular joints in their skulls from fish — ball and socket joints, much like people’s hip joints — that seem to lend themselves, but not always, to movement like in snakes,” says Casey Holliday, associate anatomy professor in the MU School of Medicine. “When you put a lot of force on things, there’s a tradeoff between movement and stability. Birds and lizards have more movement but less stability. When we applied their individual movements to the T. rex skull, we saw it did not like being wiggled in ways that the lizard and bird skulls do, which suggests more stiffness.”

Besides just improving our understanding of the T-rex’s anatomy, the study’s authors also believe their findings may be relevant to modern day medicine as well. A better understanding of how joints and ligaments interact could help advance both human and animal healthcare.

“In humans, this can also be applied to how people’s jaws work, such as studying how the jaw joint is loaded by stresses and strains during chewing,” comments lead researchers Ian Cost. “In animals, understanding how those movements occur and joints are loaded will, for instance, help veterinarians better understand how to treat exotic animals such as parrots, which suffer from arthritis in their faces.”

The study is published in the scientific journal The Anatomical Record.

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