Tyrannosaurs had fights and ate each other

A new international study found that tyrannosaurs inflicted injuries on each other and were cannibalistic, with skull evidence of a genus of tyrannosaur called Daspletosaurus suggesting they would feed on carcasses of their own dead.

Daspletosaurus was a large carnivore, slightly smaller than the famous mighty Tyrannosaurus, that lived in Canada between 77 and 74 million years ago. Like all tyrannosaurs, it was probably both an active predator and scavenger.

The specimen examined in this study, from Alberta in Canada, was not fully grown and would be considered a ‘sub-adult’ in the dinosaur world – approximately the equivalent to a human adolescent. It would have weighed about 500 kg (1,102 lbs) and measured just under 6 meters (19 ft 8 in) in length when it died.

Tyrannosaurs had some vicious fights. (Image: Luis Rey)

Researchers from the Royal Tyrrell Museum in Canada, and Queen Mary University of London in England, published their findings in the academic journal PeerJ (citation below). They found several injuries on the specimen’s skull that had occurred while it was alive.

 

Tyrannosaurs had vicious fights

Although not all the lesions can be attributed to bites, several were probably caused by tyrannosaur teeth. One bite in particular to the back of its head had broken off part of the skull and left a circular tooth-shaped puncture through the bone.

Some of the alterations to the bone’s surface suggest a number of injuries healed, indicating that those had not been fatal and the animal lived for some time after they had been inflicted.

Co-authors David Hone (left) and Darren Tanke in the Royal Tyrrell Museum with the skull of the tyrannosaur. (Image: Patty Ralrick)

Lead author Dr. David Hone, a lecturer at Queen Mary, University of London, said:

“This animal clearly had a tough life suffering numerous injuries across the head including some that must have been quite nasty.”

“The most likely candidate to have done this is another member of the same species, suggesting some serious fights between these animals during their lives.”

They ate each other

None of the injuries suggest the animal died from an attack by another tyrannosaur. However, the preservation of its bones and skull, and damage to the jaw bones show that a large tyrannosaur, maybe of the same species, fed on it after it had died.

Previous findings had shown that carnivorous dinosaurs had fights and ate each other, including tyrannosaurs.

An artist’s reconstruction of one Daspletosaurus feeding on another. (Image: Tuomas Koivurinne. Copyright: Tuomas Koivurinne)

This study is unique in that it has evidence of injuries occurring while the animal was alive, and also after it had died.

This is one of the few projects that became possible thanks to crowdfunded fundraising through the website Experiment.com. Several donors contributed to the study.

Citation: “Pre- and postmortem tyrannosaurid bite marks on the remains of Daspletosaurus (Tyrannosaurinae: Theropoda) from Dinosaur Provincial Park, Alberta, Canada,” DWE Hone & DH Tanke. PeerJ. Published 9 April, 2015. DOI: 10.7717/peerj.885.