Chapter

The Postcranial Anatomy of Australopithecus afarensis

Part of the series Vertebrate Paleobiology and Paleoanthropology pp 113-141

Date:

The Shoulder Girdle of KSD-VP-1/1

  • Stephanie M. MelilloAffiliated withDepartment of Human Evolution, Max Planck Institute for Evolutionary Anthropology Email author 

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Abstract

Extant humans and non-human apes differ markedly in shoulder girdle anatomy. Our understanding of the evolutionary history of this region was previously limited by poor fossil preservation, but over the past decade a number of impressively complete scapulae and clavicles have been described for the genus Australopithecus . However, independent analyses have reached different conclusions regarding the morphological affinity of each specimen and the degree of difference among specimens. This study provides a more detailed comparative description of the KSD-VP-1/1 scapula and clavicle, which constitute the oldest substantial evidence of hominin shoulder girdle anatomy currently known. The results suggest that the adult Australopithecus afarensis scapula is morphologically distinct, but more similar to that of modern humans than previously recognized. Some aspects of clavicle morphology are similar to non-human apes, but are also variably present in Pleistocene hominins. If comparable methodology is employed, no difference exists among Australopithecus specimens. When this morphology is considered with reference to a parsimony-based model of the chimpanzee–human last common ancestor, the adult Australopithecus shoulder girdle is derived toward morphology associated with emphasis on a manipulatory function of the pendant upper limb.

Keywords

Scapula Clavicle Australopithecus Geometric morphometrics