Dinosaur cannibals.

Popular Science makes some of the most terrifying creatures of prehistory even more terrifying with reconstructed evidence that flesh-eating dinosaurs got hungry enough to eat each other’s bones:

The researchers also found that fossils collected from the Mygatt-Moore Quarry, which lies near the border between Colorado and Utah and dates back to around 150 million years ago, bore an unusually high number of bite marks. This may mean that Allosaurus and its neighbors were living under difficult conditions and were forced to scavenge any scrap of food they could find.

“At this site they’re eating every single bit of the skeleton, anything they could get their mouth around,” says Stephanie Drumheller, a paleontologist at the University of Tennessee in Knoxville and coauthor of the new findings.

She and her team examined more than 2,300 fossils excavated from the Mygatt-Moore Quarry over a timespan of more than three decades. Typically, bones with bite marks left by predatory dinosaurs or scavengers are a rare find at sites like this. These scores and gouges can reveal a lot about ancient ecosystems, though. “Bite marks are direct evidence of an interaction—a snapshot in time,” Drumheller says. “We can use these bite marks to figure out who was eating whom [and] specific feeding behaviors.”

Based on the size and type of marks left on the bones, Drumheller and her colleagues were also able to infer that most of the marks appear to have been created by the serrated, steak-knife-like teeth of Allosaurus. In some cases, much to the researchers’ surprise, the damaged bones also belonged to an Allosaurus.

“They were probably opportunistic predators that would eat whatever they could,” Drumheller says. “They weren’t very picky; if it happened to be a distant relation, then that was fine.”

You can read the original research at PLoS ONE.