Dinosaur king Tyrannosaurus rex may have been a cannibal that preyed on its own kind, new evidence suggests.

Large bite marks on T. rex bones could only have come from other members of the same species, say scientists. The gouges are clearly the result of feeding, not fighting, according to researchers.

US scientist Nick Longrich made the discovery after finding a 65 million-year-old dinosaur fossil with unusually large bite marks.

Given the age and location of the bone, from western north America, the marks could only have been made by T. rex.

Later it became clear that the bone itself was from one of the giant meat-eaters. A search through T. rex fossils from several different museum collections revealed more evidence of cannibalism.

In total, Dr Longrich identified three foot bones, including two toes, and one arm bone with similar bite marks.

“It’s surprising how frequent it appears to have been,” said Dr Longrich, from Yale University in Connecticut, whose research is reported in the journal Public Library of Science One. “We’re not exactly sure what that means.”

Cannibalism may have been the end result of duels to the death by rival dinosaurs, the victor making a meal of his adversary.

“Modern big carnivores do this all the time,” said Dr Longrich. “It’s a convenient way to take out the competition and get a bit of food at the same time.”

The marks appear to have been made some time after death, suggesting that the cannibal dinosaur first devoured the more accessible meat before returning to pick at the smaller foot or arm bones.

Only one other dinosaur species, Majungatholus, is known to have been a cannibal. However, Dr Longrich believes the practice may have been common among dinosaurs, and closer examination of fossil bones could turn up more evidence.

Unlike many modern carnivores that hunt in packs or small groups, T. rex is believed to have been a solitary predator.

Dr Longrich said: “These animals were some of the largest terrestrial carnivores of all time, and the way they approached eating was fundamentally different from modern species.”