T. rex cousin has battle scars and signs of cannibalism
The skull of an adolescent tyrannosaur shows signs of vicious combat and of being eaten by other big dinosaurs, possibly of the same species.
The 500kg animal was a Daspletosaurus, a slightly smaller cousin of the mighty T. rex - which has already faced scientific accusations of cannibalism.
This unfortunate specimen received many vicious wounds while alive, and was then bitten by a scavenger after death.
Results of the crowd-funded study were reported in open-access journal PeerJ.
"This animal clearly had a tough life, suffering numerous injuries across the head including some that must have been quite nasty," said lead author Dr David Hone from Queen Mary, University of London.
"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."
The beast was probably about six metres long and its remains were found in a quarry in Alberta, Canada, in 1994. Its skull, housed in Alberta's Royal Tyrrell Museum, shows many injuries which Dr Hone and his colleague Darren Tanke, a senior technician at the museum, have now described in detail.
Not all of the injuries on came from bites, but many of them do match the shape of tyrannosaur teeth. There is even a circular, tooth-shaped puncture hole in the back of the head from a particularly savage bite.
The surface of the bone shows evidence of healing, which suggests that the juvenile Daspletosaurus did not die from these injuries.
Indeed, the precise cause of its early death is unknown. But additional bite marks on its jaws appear to have arrived as the beast was decaying.
This suggests it was scavenged by another large tyrannosaur, which may well have been of the same species - though this cannot be determined with any certainty.
The researchers point to another study that found evidence of cannibalism in Tyrannosaurus rex and say it "cannot be ruled out" in the related Daspletosaurus.
In the case of the Tyrannosaurus study it was easier to lay the blame on the jaws of another T. rex, because we know of no other large predators - with big enough teeth - that were alive in the same place at the same time.
This cannot be said of the Daspletosaurus, which lived 75 million years ago (10 million years before its bigger, more famous relative) in the same part of modern-day Canada as another related species, the Gorgosaurus.
"It is not possible to distinguish easily between cannibalism and feeding by another tyrannosaurid," the researchers write.
But it certainly seems that life was competitive and violent for all of these species of big predator, whose diet was a mixture of their own prey and other, scavenged meat.