A comparison of the bone density and morphology of giraffe (Giraffa camelopardalis) and buffalo (Syncerus caffer) skeletons

Unique features of giraffe Giraffa camelopardalis anatomy are its long neck and slender long limbs. Its neck vertebrae should be light and have low density to make it manoeuvrable while the limb bones should have high density to provide the strength to support the giraffe's mass. Giraffes also have a very high vertical growth rate, a diet with a high Ca:P ratio, and a skeleton that constitutes a high proportion of its body mass. To investigate whether the giraffe skeleton is affected by its anatomy and biology, giraffe bone density and morphology were compared with those of African buffalo Syncerus caffer, an artiodactyl of similar mass, more conventional anatomy, a lower vertical growth rate, and different diet. Our results show that except for minor differences the density of giraffe bones is the same as that of buffaloes. Giraffe limb bones have a slightly greater diameter and much thicker walls than equivalent bones in buffaloes. Giraffe cervical vertebrae, unlike those in buffaloes, decrease in mass with cranial distance. We conclude that giraffe biology and anatomy do not affect bone deposition or density. However, other characteristics of their skeletons seem to be adaptations to their unique anatomy.