ALBUQUERQUE — Tyrannosaurus rex had a special way of crunching bones.
A lethal combination of a powerful bite, strong teeth and repeated crunching allowed these giant predators to pulverize the bones of their prey, researchers reported October 20 at the Society for Vertebrate Paleontology’s annual meeting.
Bones have a nutritious inner cavity containing marrow and phosphate salts. But to access those goodies, most bone crushers have to be able to clamp their jaws together to crunch through the dense outer protective layer of bone. Some carnivorous mammals, like spotted hyenas and gray wolves, can do this. But bone-crushing is unknown among living reptiles because their upper and lower teeth don’t fit together, or occlude, in a way that allows them to clamp. Instead, most modern reptilian predators just swallow the bones whole to get at the nutrients.
Tyrannosaurs, including T. rex, didn’t have mammallike occluding teeth either, but fossil evidence suggests that the dinosaurs somehow pulverized the bones of their prey.
To figure out how, anatomist Paul Gignac of Oklahoma State University in Tulsa and vertebrate paleontologist Gregory Erickson of Florida State University in Tallahassee examined fossil evidence of the creatures’ dining behavior. The duo also investigated the bite forces of the only living dinosaurs, birds, as well as crocodiles, dinosaurs’ closest living relatives. Extrapolating from that evidence, the researchers estimated T. rex’s bite force and the amount of pressure the dinos’ teeth could exert at their tips.
T. rex could pulverize bones, the scientists say, thanks to a powerful bite of as much as about 34,000 newtons (more than twice as strong as of the bite force of crocodiles, the strongest of all living animals) and the amount of pressure the dinos’ teeth could exert at their tips, up to about 3,000 megapascals. The intense pressure from those teeth helped create cracks that weakened bones. T. rex would also chomp repeatedly in one region, using its advantages to get the most out of its prey.
Editor’s note: This story was updated October 24, 2018, to correct that the bite force of T. rex was as much as 34,000 newtons (not 8,000).