T. rex pulverized bones with an incredible amount of force

A strong bite and powerful teeth let the dinosaur get at nutritious marrow and salts

T. rex didn’t have the ability to clamp its jaws to crush bones, like some mammals do today. Instead, it used its powerful bite and strong teeth to pulverize the bones of its prey.

Connie Ma/Wikimedia Commons (CC BY-SA 2.0)

ALBUQUERQUE, N.M. — A powerful bite, strong teeth and repeated crunching. This is what allowed Tyrannosaurus rex to pulverize the bones of its prey. That’s the conclusion of a new analysis of the giant predator’s chomp.

Bones have an inner cavity containing marrow and other nutrients. To access those goodies, some animals crunch through the dense outer protective layer of bone. Most do so by clamping their jaws together to crush the bone. Some meat-eating mammals, like spotted hyenas and gray wolves, can do this. But bone-crushing is unknown among living reptiles. Their upper and lower teeth simply don’t fit together in a way that allows them to clamp. Instead, most modern reptilian predators swallow bones whole to get at the nutrients.

Fossil evidence suggests tyrannosaurs, including T. rex, somehow pulverized the bones of their prey. But their teeth didn’t fit together like mammals’ do. So how did they crush those bones?

Paul Gignac and Gregory Erickson teamed up to figure this out. Gignac studies body structure as an anatomist at Oklahoma State University in Tulsa. And Erickson is a vertebrate paleontologist at Florida State University in Tallahassee. That means he specializes in fossils of animals with backbones.

Together, the two looked at fossils of the teeth from T. rex and at this dino’s prey. The duo also measured the bite strength of living dino relatives. For that, they studied birds — the only living dinosaurs. They also studied crocodiles, which are dinosaurs’ closest living relatives. From these, the researchers estimated the chomping force of a T. rex bite. They also predicted how much pressure the dinos’ teeth could exert at their tips.

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My what big choppers. This closeup shows the bite of Sue, a T. rex skeleton on display at Chicago’s Field Museum.
Jill Sakai

A single bite could deliver a force up to 34,000 newtons, they now estimate. (A newton is a measure of force.) That’s more than twice the bite strength of a croc, the strongest living chomper. They also showed that the dinos’ teeth could exert intense pressure at their tips. That pressure could reach up to 3 billion pascals, the scientists estimate. (A pascal measures pressure, or the amount of force applied on an area.)

T. rex could crush bones thanks to that bite strength and the shape of its teeth, the scientists say. The massive pressure from those teeth helped create cracks that weakened bones. T. rex would also chomp over and over in the same spot to break bones.

These advantages may have helped the predator get the most out of its prey. Gignac and Erickson described their findings on October 20 here, in New Mexico, at the annual meeting of the Society for Vertebrate Paleontology.

Carolyn Gramling is the earth & climate writer. She has bachelor’s degrees in geology and European history and a Ph.D. in marine geochemistry from MIT and the Woods Hole Oceanographic Institution.

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