Palate Breadth

Palate breadth is defined by an index of external palate breadth at M2 divided by orbital height. The method used for defining the three character states used here is described earlier (see character 2). All data for the fossil hominins have been taken from B.A. Wood (1991), and data for the extant and Miocene hominids are unpublished data collected by Cameron. The mean index for the extant hominids (n = 124) is 1.66, with one standard deviation equal to 0.13. Thus, a narrow palate is defined by an index of less 1.53, intermediate breadth is between 1.53 and 1.79, while a broad palate is defined by an index greater than 1.79.

A broad palate (= 0) is observed in Graecopithecus specimen XIR-1 (original) with an index of 2.25, Australopithecus (specimen Sts 5) with an index of 2.17, P. walkeri specimen KNM-WT 17000 (cast) with an index of 2.15, P boisei with a mean index of 2.20, P robustus (specimen SK 48) with an index of 2.20, H. habilis with a mean index of 2.13 (n = 2), H. ergaster specimen KNM-ER 3733 with an index of 1.81, and H. sapiens with a mean index of 1.82 (n = 8). Intermediate palate breadth (= 1) is defined in Pongo with a mean index of 1.67 (n = 22), Gorilla with a mean index of 1.66 (n = 36), and Pan with a mean index of 1.67 (n = 66).

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