ONE MEAN BITE

By Lawrence Mondi

With its 6-in.-long razor-sharp teeth, Tyrannosaurus rex certainly had the look of a fearsome hunter. But looks aren't everything. For decades paleontologists have chewed over the suggestion that T. rex's eyes were too small, its arms too short and its legs too slow for effective hunting. A few experts have gone so far as to say that despite the monster's huge jaws, its teeth were fragile and its jaw muscles were not strong enough to capture and kill other animals. Maybe the king of the dinosaurs was just a lowly scavenger.

Or maybe not. An experiment described in the current Nature suggests that the huge carnivore did indeed have the most powerful bite in history. Researchers led by Gregory Erickson, a graduate student at the University of California, Berkeley, figured that if they could reproduce the T. rex bite marks found in fossilized Triceratops bones, they could deduce how much force had been needed to make them. So with the help of Stanford biomechanical engineers they crafted a false Tyrannosaurus tooth out of bronze and aluminum, then mounted it in a guillotine-like device and slammed it into the pelvic bone of a cow.

Their verdict: a feeding T. rex could have exerted up to 3,011 lbs. of biting force. (It would have used greater force while attacking.) A human's bite, by comparison, packs 175 lbs.; a lion's, 937; and an alligator's, just under 3,000. The research addresses only one aspect of the predator vs. scavenger question. But if scientists can find several bones with T. rex bite wounds that later healed--showing that the animals weren't already dead when they were chomped on--that might settle the debate for good.

--By Lawrence Mondi