The Cervical Vertebrae of KSD-VP-1/1

Abstract

A series of six partial cervical vertebrae were recovered in association with the KSD-VP-1/1 postcranial remains from the C2 axis to the C7 vertebral level, representing the oldest adult cervical column known in the hominin fossil record. The vertebrae of this large male australopith are more derived than those of its smaller female counterparts, and as a whole, present a biomechanical and enthesopathological signature typical of the dynamic vertical loading regime of orthograde humans. Differences between KSD-VP-1/1 and humans observed in the most cranial cervical levels appear to have insignificant functional implications, and are likely developmental reciprocates of australopith cranial morphogenesis. Despite their antiquity, the KSD-VP-1/1 vertebrae produce a surprisingly human-like kinematic signal, with a highly mobile neck, a head carriage consistent with habitual upright posture and bipedalism, and spinal cord dimensions most similar to that of modern humans.