Bite marks on a collection of bones from the Jurassic Period suggest that predatory dinosaurs called allosaurs may have resorted to cannibalism.
Stephanie Drumheller at the University of Tennessee, Knoxville, and her colleagues studied 150-million-year-old fossil bones from the Mygatt-Moore quarry in Colorado. Normally only the best bones are collected, but her team collected every bone found there. Nearly 30 per cent of the 2368 bones had bite marks on them. Usually less than 5 per cent of dinosaur bones have bite marks.
The team thinks most of the bite marks were made by allosaurs, the most common large predator found at the site. Many bite marks were found on the bones of other allosaurs. The marks could have been caused by scavenging or cannibalism. Why scavenging or cannibalism was so common at the site is unclear. One explanation is that something was unusual about this particular site; perhaps environmental conditions forced predators to scavenge or kill more. The other explanation, says Drumheller, is that this bone collection reflects the norm. The tendency of fossil hunters to leave behind damaged bones could have skewed our picture. She is trying to persuade people at other sites to try collecting every bone, too. However, this would involve a lot of work, especially if the bones are from massive species such as the allosaurs, which could grow up to 10 metres long.