Only one other dinosaur, Majungatholus, is known to have engaged in similar behavior, but paleontologists now believe Gorgosaurus (another huge meat-eater) and many other gigantic predatory dinosaurs were also cannibals.
"A lot of large carnivores tend to be cannibals -- lions, hyenas, alligators, polar bears," researcher Nicholas Longrich told Discovery News. "They're equipped to kill and eat large animals, and if you're hungry enough, fellow members of their species are just one more kind of large animal."
"Of course, small, cute, furry animals like ground squirrels are also highly cannibalistic," added Longrich, who is a paleontologist at Yale University.
He and his colleagues made the discovery, published in the latest PLoS ONE journal, while searching through western North American dinosaur fossil collections. Longrich discovered a T. rex fossil with large tooth gouges in it.
"The tooth marks are typical of tyrannosaur tooth marks, and are just too big to come from any other carnivorous dinosaur," he said, adding that T. rex teeth were about 8 inches long.
Further supporting the attribution is the fact that T. rex is known to have been the only big carnivore in western North America 65 million years ago.
When Longrich searched through additional T. rex fossil collections from several different museums, he found other evidence that this dinosaur was a cannibal. Three foot bone fossils, including two toes, and one arm fossil all retained big tooth marks due to feeding.
While it's possible that all or some of the gouges were the result of scavenging, Longrich and his colleagues think it's likely that the dino-on-dino feasting happened after fights, a meal that would help the cannibal victor.
"You're killing a competitor and getting a free meal at the same time," he explained. "The hunting is going to be better if you eat the other hunters."
Battles between these mega carnivores must have been quite a spectacle.
Read more at Discovery News
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