WAS Tyrannosaurus rex a vicious predator, or was it a scavenger,
skulking across the plains in search of carrion? Palaeontologists have debated
this for nearly a century. But a team in the US has finally shown that the king
of dinosaurs had teeth strong enough to capture and kill its food.
Greg Erickson, a PhD student at the University of California at Berkeley, and
others recreated the crushing jaw of a T. rex by attaching a bronze and
aluminium replica of one of its teeth to a hydraulic press. They then placed cow
bones in the 鈥渏aw鈥� to reproduce the bite marks discovered on a fossilised
Triceratops pelvis found in Montana.
The Triceratops pelvis had been torn from its body about 70 million
years ago and gnawed by a tyrannosaur. The dinosaur had left about 80 toothmarks
on the carcass, including punctures near the vertebrae. Long furrows suggested
that the flesh had been ripped off, but it was impossible to tell from this
specimen alone how powerful T. rex鈥檚 bite had been.
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Working with engineers at Stanford University, Erickson manoeuvred the
hydraulic jaw so that it left marks on the cow bones similar to those found on
the fossil. As the metal tooth bit into the bones, he recorded the forces
required to drive it. He calculated that T. rex鈥檚 back teeth, which had
the most leverage, would have had to exert a force of 13 400 newtons to produce
the bite marks. 鈥淚f you took a tyrannosaur tooth and set a pick-up truck on top,
that鈥檚 the kind of puncture force you鈥檇 encounter,鈥� says Erickson.
The forces could have been even greater, he suggests in the latest issue of
Nature. The hydraulic tooth penetrated the cow bones at a speed of 1
millimetre a second, which is much slower than the snapping bite of a T.
rex.
Strong teeth alone do not prove that T. rex was a predator, admits
Erickson. Indeed Jack Horner, a dinosaur expert at the Museum of the Rockies in
Bozeman, Montana, points out that most large predators alive today subdue their
prey with their front legs, something T. rex, with its scrawny
forearms, would have found difficult. But he agrees that T. rex would
have had enough bite to chew on whatever it wanted.
