The evidence comes from paleontologists Dr David Hone of Queen Mary University of London and Dr Darren Tanke of the Royal Tyrrell Museum who analyzed a fossilized skull and a mandible of the tyrannosaurine dinosaur Daspletosaurus.
Artist’s reconstruction of one Daspletosaurus feeding on another. Image credit: Tuomas Koivurinne.
Daspletosaurus was a large tyrannosaurine dinosaur that lived in what is now North America during the Late Cretaceous period, between 77 and 74 million years ago.
It’s one of the largest tyrannosaurs, and is closely related to the much larger and more recent Tyrannosaurus rex.
Like other tyrannosaurine dinosaurs, Daspletosaurus was most likely both an active predator and scavenger.
The individual of Daspletosaurus in question was excavated from the lower part of the Dinosaur Park Formation in Alberta, Canada. It was a sub-adult in dinosaur terms – just under 6 m long and around 500 kg.
Dr Hone and Dr Tanke found numerous injuries on its skull that occurred during life, at least some of which were likely inflicted by another Daspletosaurus. It was also bitten after death in an apparent event of scavenging by another tyrannosaur.
“Although not all of them can be attributed to bites, several are close in size and shape to the teeth of tyrannosaurs. In particular one bite to the back of the head had broken off part of the skull and left a circular tooth-shaped puncture though the bone,” the scientists said.
Daspletosaurus skull with numerous injuries. Scale bar – 10 cm. Image credit: David Hone.
“The fact that alterations to the bone’s surface indicate healing means that these injuries were not fatal and the animal lived for some time after they were inflicted.”
“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,” said Dr Hone, who is the first author of the paper published in the journal PeerJ.
There is no evidence that this Daspletosaurus died at the hands, or mouth, of another tyrannosaur.
However, the preservation of the skull and other bones, and damage to the jaw bones show that after the specimen began to decay, a large tyrannosaur (possibly Daspletosaurus) bit into the animal and presumably ate at least part of it.
“Combat between large carnivorous dinosaurs is already known and there is already evidence for cannibalism in various groups, including tyrannosaurs. This is however an apparently unique record with evidence of both pre- and post-mortem injuries to a single individual.”
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Hone D & Tanke D. 2015. Pre- and postmortem tyrannosaurid bite marks on the remains of Daspletosaurus (Tyrannosaurinae: Theropoda) from Dinosaur Provincial Park, Alberta, Canada. PeerJ 3: e885; doi: 10.7717/peerj.885
