Monday, September 7, 2009

T. rex bites: model suggests powerful jaws

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A recent study suggests the bite of Tyrannosaurus rex was as powerful as that of the modern American alligator. Replicas of T. rex teeth were shown to exert an approximate force of 3,000 pounds, almost 20 times the force of a human bite.

Full Text :COPYRIGHT 1997 Kalmbach Publishing Company
Scientists have long-debated the feeding habits of Tyrannosaurus rex. It scavenged. No, it preyed. It lumbered. No, it was fleet of foot. It had weak teeth. No, strong. And, unfortunately, the fossil record hasn't revealed much about how the dinosaur obtained its food.

But a recent study lends evidence to one side of the debate. Gregory Erickson, a graduate student in biology at the University of California, Berkeley, and engineers from Stanford University, showed that T. rex could devour its meals with a bite as powerful as that of the American alligator.

To arrive at their conclusion, Erickson and his colleagues simulated T. rex bite marks found in the fossilized ilium (a flat part of the pelvis) of a Triceratops. They used replicas of T. rex teeth and a specially designed guillotinelike device to inflict puncture wounds in cow bones, similar in structure to Triceratops bones.

The deepest of 58 bite marks on the Triceratops ilium measures 9 centimeters, about three-and-a-half inches. To inflict a gouge of that size in the cow bones using the replicated teeth, the device exerted about 1,440 pounds of force in the anterior teeth, those in the front of the mouth. At that level, the force for the posterior teeth, those at the back of the mouth, would have been 3,011 pounds.

For comparison, consider humans, whose posterior teeth bite with a wimpy 175 pounds of force, and the American alligator, whose jaws snap shut with a deadly force of about 3,000 pounds in the posterior teeth. The simulation was for feeding marks, not for the more powerful killing marks.

By calculating bite force, the scientists were able to estimate the strength of a jaw that could endure such stress. According to Erickson, when the first tyrannosaurs were found, their teeth didn't show many wear marks. To some, this indicated the dinosaur ate rotting flesh. "We know now tyrannosaurs regularly replaced their teeth and this explains their general lack of wear," says Erickson.

Scientists also thought the jaws on T. rex were too slender to sustain the force necessary during a struggle with prey. "But if the dentition can produce these kinds of forces," says Erickson, "then we estimate that the jaw could support it."

Though the finding doesn't prove T. rex was a predator, says Erickson, "It shows [its] teeth and jaws were strong enough to endure the stresses associated with prey struggles."

Source Citation:Staedter, Tracy. "T. rex bites: model suggests powerful jaws." Earth 6.n1 (Feb 1997): 13(1). Academic OneFile. Gale. BROWARD COUNTY LIBRARY. 7 Sept. 2009

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