When food was scarce 66 million years ago, tyrannosaurs did not hesitate to eat a member of their own family in order to survive, a new study revealed. Researchers from the Geological Society of America (GSA) discovered distinctive teeth marks on new fossil bones that suggest the large carnivores might have also been cannibals.
"We were out in Wyoming digging up dinosaurs in the Lance Formation," Matthew McLain, a paleontologist from Loma Linda University in California, said in a news release. "Someone found a tyrannosaur bone that was broken at both ends. It was covered in grooves. They were very deep grooves."
After further analyzing the grooves, researchers concluded they were made by a large animal that pulled the flesh from the bone in a perpendicular direction. This is the same way humans eat meat from a chicken wing, the release noted.
One groove located at the larger end of the bone stood out to the researchers because it contained several smaller parallel groves. This indicates that as the tyrannosaur was pulling meat from the bone they were also turning their head from side to side in order to sever and free it more easily, according to the release.
These grooves also suggest that the large predators had serrated teeth. This allowed researchers to narrow down the possible diners to theropods, such as the T. rex. Since the only large theropods found in the Lance Formation are two tyrannosaurs, this means that these bite marks were an act of cannibalism, researchers explained in their study.
"This has to be a tyrannosaur," McLain added. "There's just nothing else that has such big teeth."
Researchers also determined the tyrannosaur was dead at the time that it was being eaten. However, further research is needed in order to determine if the cannibal was also the killer or simply scavenging.
"Exactly who did the eating that day, in the Late Cretaceous, could still be sorted out by the same grooves," McLain said in a statement.
Ultimately, this study sheds light on the behaviors of massive dinosaurs during this time, and that cannibalism did occur occasionally. McLain will be presenting the findings at the GSA's annual meeting.
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