Humeral outlines in some hominoid primates and in plio-pleistocene hominids.

A method of drawing outlines of the distal end of the humerus is presented and carried out on some pongids (Pan troglodytes, Pan paniscus, Pongo pygmaeus), on modern man, and on some casts of Plio-Pleistocene hominids. It appears that these outlines are good indicators of the overall morphology and permit the distinguishing of the different hominoids. For example, the morphology of the pillars surrounding the fossa olecrani is useful for this purpose. In modern man, the lateral pillar is quadrangular, contrasting with the triangular medial one. In pongids, both of them are triangular; however, it is possible to note differences between Pongo and Pan. In the South Asian ape, there is a stronger anteroposterior flattening of the pillars as well as the diaphysis. The similarity of the shape of the pillars might be considered as a result of an adaptation to suspension. The differences might be due to different weights of the animals. Plio-Pleistocene hominids are variable with regard to the morphology of this region. For example, Gombore IB 7594 is similar to Homo. KNMER 739 exhibits features intermediate between hominids and pongids. Finally, AL 288.1M is closer to pongids. These results confirm a previous anatomical work.