The gouges had to have been made by a large carnivore, he said, and when the mystery fossils were deposited 65 million years ago, T. rex was the only North American carnivore large and toothy enough to make such marks.
But the seemingly routine find took a macabre turn when Longrich discovered one of the bitten bones belonged to a T. rex—making it apparent evidence of cannibalism.
This toe bone “has giant theropod bite marks, and the only one there [at that time] was T. rex,” he said. “There was really no other conclusion I could come to.”
Further analysis in several fossil collections turned up three more similarly bittenT. rex bones.
Longrich and colleagues speculate the giant predators may have engaged in cannibalism with some regularity—but it’s unknown whether the dinosaurs fought to the death or simply scavenged T. rex corpses.