Sauropodomorphs were apparently healthy animals and the vast majority of specimens show little or no evidence of paleopathological conditions. One reported possible ailment found in specimens of Diplodocus, Apatosaurus, and Camarasaurus is diffuse idiopathic skeletal hyperostosis (better known by its medical acronym, DISH), a condition where ligaments running laterally alongside the vertebrae become ossified. This condition gives the vertebrae a fused appearance, although the vertebrae themselves are not actually fused. In those sauropods so affected, some of the caudal vertebrae were bonded together by this ossification, which made them stiffer structures. Hence, one explanation for the frequency of this condition is that it represents an adaptation more than a malady. Sauropod trackways show no clear evidence of tail dragging, for example, and a stiffened tail would have prevented the formation of such a trace fossil. Interestingly, despite their often-huge sizes, no sauropods studied so far have shown any unequivocal signs of stress fractures or osteoarthritis.
Sauropodomorphs were subject to consumption by carnivores, specifically by their theropod contemporaries. Evidence for their role in Mesozoic food chains is largely expressed through toothmarks on sauropod bones, such as the documented numerous toothmarks on Apatosaurus bones that were probably inflicted by its Late Jurassic contemporary, Allosaurus (Chapter 14). One assumption is that such tooth-marked sauropods were the spoils of predation, but no definitive evidence supports that sauropods were the victims of predation more or less often than their corpses were scavenged. Indeed, the sheer size of some sauropod species, as well as trackway evidence showing that sauropods moved together in herds, have been proposed as protective measures that discouraged predation. In similar modern terrestrial predator-prey relationships between large herds of herbivores and pack-hunting animals, lions have been known to isolate and kill very young or weak members of an elephant herd. However, the mere presence of the herd structure, compounded with the sizes of adult elephants and their fierce protectiveness, is normally sufficient deterrent to predation. This means that a successful hunt on an elephant is rare. With this simile in mind and the little evidence that is known, sauro-podomorphs probably were not subject to any more predation than other herbivorous dinosaurs. In effect, they may have been even more resistant to death through such means, despite the enormous amount of potential protein that some sauro-podomorph species could have provided for predators.
Was this article helpful?