Supraorbital Torus Thickness

This feature is distinct from supraorbital torus form because it measures the thickness of the torus from its midpoint (inferosuperior chord distance). This value is divided by orbital height to give an index value. The extant hominoid mean of 0.22 and one standard deviation of 0.07 gives an intermediate range of 0.15-0.29. Data for the extant and fossil Miocene homi-noids is unpublished data held by Cameron (unless stated otherwise), while all data of the fossil hominins has been calculated from the data provided in B.A. Wood (1991). It was also noted that the mean for H. sapiens was below the minimum value generated for the extant hominid (0.11). Thus, an additional character state of a very gracile torus (< 0.11) is recognized; no hominids were beyond the maximum extant hominid value of 0.43.

A thick supraorbital torus (= 0) is observed in P. boisei with a mean index of 0.33 (n = 2), K. rudolfensis with a mean of 0.30 (n = 2), and Gorilla also with a mean index of 0.30 (n = 35). While no metric data are available for Sahelanthropus, the supraorbital is shown by Brunet et al. (2002) to be beyond the range observed in Gorilla. Thus, it is allocated to the same character state as this great ape. The intermediate state (= 1) defines the primitive hominid condition and is observed in Dryopithecus specimen RUD 77 (data from Kordos & Begun, 1997) with an index of 0.15, Graecopithecus specimen XIR-1 (original) with an index of 0.27, Australopithecus with a mean of 0.23 (n = 2), P walkeri specimen KNM-WT 17000 with an index of 0.28, P robustus with an index of 0.29 (n = 2), H. habilis with an index of 0.23 (n = 2), H. ergaster specimen KNM-ER 3733 with an index of 0.22, Pongo with a mean of 0.16 (n = 22), and Pan with an index of 0.20 (n = 66). A reduced torus (= 2) is present in H. sapiens with a mean of just 0.10 (n = 6).

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