Upper Facial Breadth

The method used for defining the indices and ranges of variability and resulting character states are described earlier (see character 2). The overall breadth of the upper face is important because it gives a relative statement concerning the lateral expansion of the upper face. All data for the fossil hominins have been taken from B.A. Wood (1991); data for the Miocene and extant hominids are unpublished data collected by Cameron, though partly provided in Cameron (1997a, 1997b, 1998). The index is bi-frontomalare temporale/orbital height. The extant hominid mean is 2.94 (n = 122), with one standard deviation of 0.34. Thus, the intermediate condition is between 2.60 and 3.28, while broad is larger than 3.28, and narrow is less than 2.60. It was also noted that Graecopithecus, with an index of 4.44, lies well beyond the extant hominid maximum value of 3.81, so it is allocated to an additional character state, "extremely broad" (see next paragraph).

A narrow upper face (= 0) defines Pongo with a mean index of 2.47 (n = 20). Intermediate upper facial breadth (= 1) is observed in Dryopithecus specimen RUD 77, with an estimated index of 2.81 (data supplied in Kordos & Begun, 1997), Sahelanthropus specimen TM 266-01-060-1 has an index of 2.83 (data from Brunet et al., 2002), Australopithecus has a mean index of 3.11 (n = 2), P Walkeri specimen KNM-WT 17000 (cast) has an index of 2.86, H. habilis has a mean index of 3.23 (n = 2), Gorilla has a mean of 3.11 (n = 36), Pan has a mean index of 2.99 (n = 65), and H. sapiens has a mean index of 3.13 (n = 176 [data from Thorne, 1976]). A broad face (= 2) is observed in P boisei, with a mean index of 3.29 (n = 2), P robustus specimen SK 49, with a mean index of 3.57, K. rudolfensis, with a mean index of 3.57 (n = 2), and H. ergaster, with a mean index of 3.32 (n = 2). While there is evidence of some post depositional distortion in Graecopithecus specimen XIR-1, it clearly has a broad face. An estimate of facial breadth and orbital height taken from the original specimen gives a significant value of 4.44, which is well beyond the maximum value generated for the extant hominid, at 3.81 (n = 122). Thus, it is allocated to its own character state, an "extremely broad" upper face (= 3).

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