Zygomatic Insertion Height

This feature relates to the insertion of the zygomaticoalveolar crest onto the alveolar border. This feature is of functional interest, because it will bear directly on the leverage of the masseter muscles as well as partly defining facial height. Two conditions are recognized, a low insertion (= 0) and a high insertion (= 1). A low insertion is observed in Kenyapithecus (McCrossin & Benefit, 1997 [contra Begun & G├╝lec, 1997; Begun et al., 1997]), Graecopithecus (Begun et al., 1997), both species of Kenyanthropus, and P walkeri (M.G. Leakey et al., 2001). A high insertion is observed in Dryopithecus (Begun et al., 1997), Sahelanthropus (Brunet et al., 2002), Australopithecus (Rak, 1983), P. boisei (Tobias, 1967), P. robustus

(M.G. Leakey et al., 2002), H. ergaster (Walker & Leakey, 1993), Pongo, Gorilla, Pan, and H. sapiens. While Kimbel et al. (1994) do not discuss the height of the insertion in Praeanthropus, specimen A.L. 444-2 is observed to have a relatively high insertion (their Figure 2). Also, while B.A. Wood (1991) considers H. habilis specimen KNM-ER 1813 to have a low insertion relative to specimen KNM-ER 1470, it is still relatively high; that is, within the range of the extant hominids.

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