Node

This node represents the common hypothetical ancestor of the hominins (sensu DWC), including Sahelanthropus and the garhi group, suggesting that the origin of the hominins is significantly deeper in time then previously considered (if we truly accept Sahelanthropus as being a basal hominin, which DWC does but CPG does not), and that the proto-australopithecines had little if anything to do with the origins of the hominins and represent an additional Plio/Pleistocene hominid radiation event, resulting in the extinction of numerous hominid species.

This basal hominin is defined by the emergence of an asterionic notch. Also, the mastoids are inflated, and the nuchal plane is less inclined. The origin of the masseter is high and the nasal clivus is flat. Following on from the previous node, the lingual cusps and buccal cusps crowd the occlusal surface. The mandibular symphysis is near vertical and the mandible as a whole is robust. The extramolar sulcus has increased in breadth. Finally, P3 metaconids are present and the mesiobuccal expansion is weak to absent. Sahelanthropus has a thick supraorbital, no frontal sulcus, and no sagittal crest. The cranial base is narrow and facial hafting is similar to that observed in Gorilla (suggested by DWC to be a homoplasy). The zygo-matic has moved even farther anteriorly and the nasal clivus is short and high. Molar enamel has increased, and the upper molars tend to be square in shape (another homoplasy shared with Gorilla). The garhi hominins have a reduction in torus robusticity and development, with increased development of the frontal sinus, and the nasal clivus is convex.

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