Upper Molar Morphology

This character is related to masticatory demands and is of phylogenetic significance, not only given the concept of phylogenetic niche conservatism, but also because of the apparent high heritability of dental development processes and occlusal morphology (see Jernvall, 1995; Teaford, 2000). This character, while undoubtedly influenced by molar enamel thickness, is not strongly correlated, and each represents a distinct feature. For example, Kenyapithecus has relatively thick enamel with inflated cusps and cristae, while Ankarapithecus also has relatively thick enamel. It, however, has undeveloped cusps and cristae (see Andrews & Alpagut, 2002).

The primitive condition is observed in Dryopithecus, which has high and developed cusps-cristae formation (= 0) (Begun, 1994a/b; Andrews et al., 1996), Gorilla, Pan, and Praeanthropus (T.D. White et al., 1983). Ardipithecus is described as having a similar overall morphology to that of Praeanthropus (T.D. White et al., 1994). Low inflated cusps with limited or no cristae development (= 1) are observed in Kenyapithecus (Leakey, 1962; Andrews & Walker, 1976; Ward & Durren, 2002), Graecopithecus (de Bonis et al., 1990; de Bonis & Koufos, 1993, 2001), Sahelanthropus (Brunet et al., 2002), the "anamensis group" (M.G. Leakey et al., 1995; C.V. Ward et al., 2001), Australopithecus (T.D. White et al., 1983), H. habilis (Tobias, 1991), K. rudolfensis (B.A. Wood, 1991), H. ergaster (B.A. Wood, 1991), and H. sapiens. Low cusps with extensive enamel wrinkling (= 2) are observed in Pongo (S. Ward, 1997); while a low, flat "grinding stone-like" occlusal surface (= 3) is observed in P. boisei and P robustus (Tobias, 1967; T.D. White et al., 1983).

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