Scapula, clavicle, and proximal humerus

This chapter describes parts of four scapulae, two clavicles, and three proximal humeri, and provides information on the functional anatomy of the Sterkfontein hominin pectoral girdle and shoulder joint. The clavicle resembles that of other hominins, which indicates a more horizontal orientation than in apes. Comparative analysis of these scapulae, though, suggests that the glenohumeral joint of  Australopithecus africanus  is more cranially oriented than typical for humans, perhaps even more so than seen in East African early hominins. This morphology may also indicate features of dorsal scapular shape, which could impact potential areas of attachment as well as line of action of dorsal rotator cuff muscles. The glenohumeral joint morphology and orientation implies the possibility of more arboreality in the  A. africanus  locomotor repertoire.