Congenital cervical pathologies in the saber-toothed cat Smilodon fatalis and the cave bear Ursus spelaeus – Nearing extinction in Late Pleistocene times

Inbreeding is a known cause for an increased incidence of vertebral malformations. Inbreeding can be the result of geographical isolation of a diminishing wild population. A high incidence of transitional vertebrae has for example been reported in declining, inbred populations of Pleistocene megafauna. Rare cervical C6-C7 intrasegmental tranistions were found in Smilodon fatalis from the late Pleistocene of North America and Ursus spelaeus from Europe indicating inbreeding during their extinction process. During the late Pleistocene growing human presence increased the hunting pressure on the megafaunal species. We can conclude that human activities reduced the populations of late Pleistocene megafauna in a short period, and that this enhanced the tendency of inbreeding affecting the health of the animals.