The secrets behind T. rex's bone crushing bites: Researchers find T. rex could crush 8,000 pounds

May 17, 2017
Restoration of a walking T. rex. Credit: Wikipedia/ CC BY-SA 3.0

The giant Tyrannosaurus rex pulverized bones by biting down with forces equaling the weight of three small cars while simultaneously generating world record tooth pressures, according to a new study by a Florida State University-Oklahoma State University research team.

In a study published today in Scientific Reports, Florida State University Professor of Biological Science Gregory Erickson and Paul Gignac, assistant professor of Anatomy and Vertebrate Paleontology at Oklahoma State University Center for Health Sciences, explain how T. rex could pulverize bones—a capacity known as extreme osteophagy that is typically seen in living carnivorous mammals such as wolves and hyenas, but not reptiles whose teeth do not allow for chewing up bones.

Erickson and Gignac found that this prehistoric reptile could chow down with nearly 8,000 pounds of , which is more than two times greater than the of the largest living crocodiles—today's bite force champions. At the same time, their long, conical teeth generated an astounding 431,000 pounds per square inch of bone-failing tooth pressures.

This allowed T. rex to drive open cracks in bone during repetitive, mammal-like biting and produce high-pressure fracture arcades, leading to a catastrophic explosion of some bones.

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

The researchers built on their extensive experience testing and modeling how the musculature of living crocodilians, which are close relatives of dinosaurs, contribute to bite forces. They then compared the results with birds, which are modern-day dinosaurs, and generated a model for T. rex.

From their work on crocodilians, they realized that high bite forces were only part of the story. To understand how the giant dinosaur consumed bone, Erickson and Gignac also needed to understand how those forces were transmitted through the teeth, a measurement they call tooth pressure.

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

In current day, well-known crunchers like spotted hyenas and gray wolves have occluding teeth that are used to finely fragment long bones for access to the marrow inside—a hallmark feature of mammalian osteophagy. Tyrannosaurus rex appears to be unique among reptiles for achieving this mammal-like ability but without specialized, occluding dentition.

The new study is one of several by the authors and their colleagues that now show how sophisticated feeding abilities, most like those of modern mammals and their immediate ancestors, actually first appeared in reptiles during the Age of the Dinosaurs.

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TheGhostofOtto1923
5 / 5 (1) May 17, 2017
Well we won't know for sure until we rebuild one in 50-60 years. By that time we should know enough about gene expression to be able to extrapolate genetic structure from the info we can gleen from the fossil record in combination with what we know about how genes determine form and function in existing animals.

IOW we won't need genes from amber-preserved dinosaur blood. Fossils will tell us enough to recreate the animals they came from.
Dug
1 / 5 (1) May 17, 2017
The author needs to understand that stating "8,000 pounds of force" is meaningless - especially in the titlle. Without the surface area that force is applied over the number is incomplete and communicates nothing. Either express the bite force in newtons or PSI if you want to communicate relative and or comparable force values - as you did in some places, but that doesn't seem correct when compared to the info below.

"The "winners"—saltwater crocodiles—slammed their jaws shut with 3,700 pounds per square inch (psi), or 16,460 newtons, of bite force. By contrast, you might tear into a steak with 150 to 200 psi (890 newtons)." (http://news.natio...ongest/)
MarsBars
not rated yet May 18, 2017
The author needs to understand that stating "8,000 pounds of force" is meaningless - especially in the titlle. Without the surface area that force is applied over the number is incomplete and communicates nothing. Either express the bite force in newtons or PSI if you want to communicate relative and or comparable force values...

I could have sworn that I read: "At the same time, their long, conical teeth generated an astounding 431,000 pounds per square inch of bone-failing tooth pressures."

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