Artists reconstruction of combat between two Daspletosaurus. Image © Luis Rey
Anyone who’s ever seen ‘Jurassic Park’ knows tyrannosaurs are terrifying. But a new study proves we had no idea just how terrifying. It turns out these biggest and baddest large predators of the dinosaur era fought each other viciously – and engaged in intra-species feeding … you know, cannibalism.
If we want to know more about how tyrannosaurs lived, and what their behaviour and day-to-day life was like (without the use of a handy time machine), we can turn to the fossil record. It preserves snapshots for us from the time of the dinosaurs, and if we ask the right questions, it can tell us a lot. Did tyrannosaurs fight each other? Did they engage in cannibalism like many mammalian predators we know today? New research led by Dr Dave Hone of Queen Mary University of London, and published in the journal PeerJ, provides some answers.
Canada, some 75 million years ago, was home to a tyrannosaur dinosaur known as Daspletosaurus – a close cousin of the infamous ‘Tyrant King’ itself, Tyrannosaurus rex. Although not quite as big as Tyrannosaurus, this beast was still both an active hunter and an opportunistic scavenger, much like modern-day big predators. Its name Daspletosaurus even means ‘frightful lizard’, an indication of its fearsome reputation.
The researchers studied a ‘teenage’ specimen of Daspletosaurus from Alberta, which was found with evidence of numerous bite wounds and puncture marks on its skull and lower jaw. The size and shape of one particular bite to the back of the head suggests it was probably inflicted by a rival Daspletosaurus. The ferocious bite (evidence of the crushing power of tyrannosaur jaws) broke off part of the skull and left a circular tooth-shaped puncture though the bone – but it wasn’t fatal. Even in fossils this old, it’s possible to see evidence that the bone re-healed after the attack, indicating that the animal survived for some time afterwards (though probably in some pain).
View of the right lower jaw of Daspletosaurus skull. This was bitten at the break point between the bones by another large tyrannosaur. (Scale bar is 10 cm). Image © David Hone
“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,” explains Hone.
But here’s where things get interesting. Further impressions show that another animal took a big bite out of our Daspletosaurus – but this time the wounds were inflicted after death. We can tell these are postmortem bites because of the lack of healing indicators on the bones. Based on the size of the bite marks, the likely culprit was, once again, another Daspletosaurus. (Clearly, staying alive took priority over any potential eating-your-own-kin taboos.)
While there’s evidence for combat, play and even cannibalism in numerous carnivorous dinosaurs, this is the first time that clues pointing to such behaviours have been found preserved on one individual specimen.
Artists reconstruction of one Daspletosaurus feeding on another. Image © Tuomas Koivurinne
Being able to assign feeding or combat marks to a particular animal is often difficult, but in this case we know it must have been a large-bodied tyrannosaur, and Daspletosaurus certainly fits the bill, being the only tyrannosaur from Canada at this time.
The question of why Daspletosaurus engaged in combat is up for debate. The (pre-mortem) bite marks could represent some sort of ritualistic combat for territorial reasons. Or perhaps the wounds were inflicted in a clash for social or sexual dominance – the idea of huge tyrannosaurs fighting for a mate is certainly appealing to the imagination. Of course, we could just be dealing with a moody teenage tyrant who was misunderstood by all the other dinosaurs and used fighting as a way of masking his true feelings.