Palaeopathological changes in a population of 'Albertosaurus sarcophagus' from the Upper Cretaceous Horseshoe Canyon Formation of Alberta, Canada

Over the past decade, excavations of a monodominant theropod bonebed from the lower Maastrichtian beds of the Horseshoe Canyon Formation have recovered a minimum number of 26 individuals of the tyrannosaur, 'Albertosaurus sarcophagus'. Examination of skeletal elements from the bonebed revealed a small number of abnormalities from at least two individuals. These include bony spurs (enthesophytes) of unknown origin on three pedal phalanges. Well-healed fracture calluses are present on two rib shafts and a gastralia element. The left dentary of one adult preserves both healed and unhealed parallel bite marks and a perforative lesion attributable to a partially healed, mechanically induced puncture wound. Unfortunately, the limited range in the types and frequencies of pathological changes provides only little information on the distribution of such phenomena but may be suggestive of the overall "health" of the population.