Like Father, Like Son: Assessment of the Morphological Affinities of A.L. 288-1 (A. afarensis), XXXX 7 (A. africanus) and Omo 119-73-2718 (Australopithecus sp.) through a Three-Dimensional Shape Analysis of the Shoulder Joint.

@entity1 @entity2031 @entity4840 @entity146
UNASSIGNED: The postcranial evidence for the Australopithecus genus indicates that australopiths were able bipeds; however, the morphology of the forelimbs and particularly that of the shoulder girdle suggests that they were partially adapted to an arboreal lifestyle. The nature of such arboreal adaptations is still unclear, as are the kind of @entity146 in which australopiths might have engaged. In this study we analyzed the shape of the shoulder joint (proximal humerus and glenoid cavity of the scapula) of three australopith specimens: A.L. 288-1 (A. afarensis), @entity2031 7 (A. africanus) and Omo 119-73-2718 (Australopithecus sp.) with three-dimensional geometric morphometrics. The morphology of the specimens was compared with that of a wide array of living anthropoid taxa and some additional fossil hominins (the Homo erectus specimen KNM-WT 15000 and the @entity4840 specimen Tabun 1). Our results indicate that A.L. 288-1 shows mosaic traits resembling @entity1 and Pongo, whereas the @entity2031 7 shoulder is most similar to the arboreal apes and does not present affinities with @entity1 . Omo 119-73-2718 exhibits morphological affinities with the more arboreal and partially suspensory New World monkey Lagothrix. The shoulder of the australopith specimens thus shows a combination of primitive and derived traits (humeral globularity, enhancement of internal and external rotation of the joint), related to use of the arm in overhead positions. The genus Homo specimens show overall affinities with @entity1 at the shoulder, indicating full correspondence of these hominin shoulders with the modern @entity1 morphotype.
