Biology

T-Rex's bone-shattering bite was much worse than its bark

T-Rex's bone-shattering bite w...
Researchers have calculated the bite force of a Tyrannosaurus Rex to be about 8,000 pounds, twice as powerful as a modern crocodile
Researchers have calculated the bite force of a Tyrannosaurus Rex to be about 8,000 pounds, twice as powerful as a modern crocodile
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This section of Triceratops pelvis shows some 80 T-rex bite marks, indicating a "puncture and pull" pattern of biting
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This section of Triceratops pelvis shows some 80 T-rex bite marks, indicating a "puncture and pull" pattern of biting
Using the jaw musculature of modern crocodiles, Florida State University researchers calculated that the T-rex might have had a bite force of 8,000 lb (35,586 N), and 431,000 psi
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Using the jaw musculature of modern crocodiles, Florida State University researchers calculated that the T-rex might have had a bite force of 8,000 lb (35,586 N), and 431,000 psi
Researchers have calculated the bite force of a Tyrannosaurus Rex to be about 8,000 pounds, twice as powerful as a modern crocodile
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Researchers have calculated the bite force of a Tyrannosaurus Rex to be about 8,000 pounds, twice as powerful as a modern crocodile

Few animals capture the imagination quite like the Tyrannosaurus rex – even if it wasn't the biggest predator to ever stalk the Earth, and it may have sounded more bird than beast. But a new study shows that the King may still deserve its crown, thanks to a terrifying set of jaws that could deliver one of the strongest bites of any land animal in history. It's an ability that T-rex probably used to pulverize and eat the bones of its unfortunate prey.

A group of scientists from Florida State University began by studying the bite force of crocodiles and alligators, which are at the top of today's list of animals you don't want to find yourself between the jaws of. In 2012, the team found that a saltwater crocodile packed a bite of 3,700 pound-force (16,460 newtons), By comparison, a human vigorously tearing into a steak tops out at around 200 lbf (890 N).

Using the jaw musculature of modern crocodiles, Florida State University researchers calculated that the T-rex might have had a bite force of 8,000 lb (35,586 N), and 431,000 psi
Using the jaw musculature of modern crocodiles, Florida State University researchers calculated that the T-rex might have had a bite force of 8,000 lb (35,586 N), and 431,000 psi

Using the jaw musculature of crocodiles as a starting point, the Florida State researchers compared the reptilian figures with those of birds, a closer modern relative of dinosaurs, to create a model for the biting power of a T-rex. The dinosaur, they found, could chow down with about 8,000 lbf (35,586 N), more than twice the force of a saltwater croc. But the team points out that in practical terms, there's more to the story than that one number.

"Having high bite force doesn't necessarily mean an animal can puncture hide or pulverize bone, tooth pressure is the biomechanically more relevant parameter," says Gregory Erickson, co-author of the study. "It is like assuming a 600 horsepower engine guarantees speed. In a Ferrari, sure, but not for a dump truck."

Tooth pressure is determined by how the shape of the teeth focuses the pressure into a smaller point, and the T-rex's long, cone-shaped chompers were perfect for piercing flesh and shattering bone. Channeling the force, a Tyrannosaurus bite could impart as much as 431,000 pounds per square inch (psi), which helped the animal pulverize the bones of its prey to give it a nutritional advantage over other predators of its day. To compare, saltwater crocs were measured at 360,000 psi.

"It was this bone-crunching acumen that helped T-rex to more fully exploit the carcasses of large horned-dinosaurs and duck-billed hadrosaurids whose bones, rich in mineral salts and marrow, were unavailable to smaller, less equipped carnivorous dinosaurs," says Paul Gignac, co-author of the study.

This section of Triceratops pelvis shows some 80 T-rex bite marks, indicating a "puncture and pull" pattern of biting
This section of Triceratops pelvis shows some 80 T-rex bite marks, indicating a "puncture and pull" pattern of biting

This feeding style is very different from modern crocodiles, which bite to kill before swallowing their meals mostly whole. Due to their tooth structure, as well as bite marks found on Triceratops bones, the researchers suggest that the T-rex ate with a biting and chewing pattern, in the style of modern mammals like hyenas and wolves. That means this feeding pattern arose earlier than previously thought.

The research was published in the journal Scientific Reports.

Source: Florida State University

4 comments
McDesign
"a Tyrannosaurus bite could impart as much as 431,000 pounds per square inch (psi), which helped the animal pulverize the bones of its prey to give it a nutritional advantage over other predators of its day. To compare, saltwater crocs were measured at 360,000 psi." So - mild steel has a compressive strength of ~60-80,000 psi - what are those tooth tips made of? Anyone explain?
ezeflyer
TRex had no molars so it could not chew, grind and "pulverize" bones. It could bite and pull off off chunks of flesh and bone perhaps by pinning down the meat with its powerful back legs to get leverage, then swallow the chunks like a croc.
Stradric
@ezeflyer: I suspect you didn't read the article.
Ralf Biernacki
Not just mild steel---431000 PSI is well beyond the ultimate strength of the best maraging steels, and most other materials out there. This kind of pressure would pulverize, all right---it would thoroughly pulverize the teeth attempting to exert it. Perhaps the scientists ought to double-check their data. I suspect the error lies in assuming an unrealistically small area over which the pressure is concentrated---dividing 8000 lbf by the 431000 PSI gives an effective area of just 12 square millimeters, but this is without taking into account the moment arm of the jaw. Estimating a mechanical (dis)advantage of 1/6 based on moment arms eyeballed from the skull image, the effective area would have to be 2 square millimeters to produce such stresses---about the head of a pin. This is not realistic.