Geometric morphometric analysis of the crown morphology of the lower firstudpremolar of hominins, with special attention to Pleistocene Homo

摘要

This article is the third of a series that explores hominin dental crown morphology by means of geometricudmorphometrics. After the analysis of the lower second premolar and the upper first molar crownudshapes, we apply the same technique to lower first premolar morphology. Our results show a clearuddistinction between the morphology seen in earlier hominin taxa such as Australopithecus and Africanudearly Homo, as well as Asian H. erectus, and more recent groups such as European H. heidelbergensis, H.udneanderthalensis, and H. sapiens. The morphology of the earlier hominins includes an asymmetricaludoutline, a conspicuous talonid, and an occlusal polygon that tends to be large. The morphology ofudthe recent hominins includes a symmetrical outline and a reduced or absent talonid. Within this laterudgroup, premolars belonging to H. heidelbergensis and H. neanderthalensis tend to possess a small andudmesiolingually-displaced occlusal polygon, whereas H. sapiens specimens usually present expanded andudcentered occlusal polygons in an almost circular outline. The morphological differences among Paranthropus,udAustralopithecus, and African early Homo as studied here are small and evolutionarily lessudsignificant compared to the differences between the earlier and later homin taxa. In contrast to the lowerudsecond premolar and the upper first molar crown, the inclusion of a larger hominin sample of lower firstudpremolars reveals a large allometric component.