Glenoid Fossa Depth

Four character states are defined: deep, variable, intermediate (between deep and shallow), and a shallow fossa. The depth of the glenoid process is clearly associated with the requirements of the masticatory apparatus (temporomandibular joint) and is of functional significance. This is also aligned to developmental processes associated with osteoclast/osteoblast activity and bone drift, which will affect mandibular and lower facial form (Enlow & Hans, 1996). This character is measured as an index of depth perpendicular to the Frankfurt horizontal, that is from the base of the articular eminence to the apex of the fossa/breadth of the eminence from the articular tubercle to the entoglenoid process.

The allocation of hominids to character states follows Strait et al. (1997) and Strait and Grine (2001). The Miocene hominids help define the primitive condition as deep (= 0). In the case of the Miocene hominids, no such measurements were generated (data not available). In all cases, the Miocene hominids are described as having a deep fossa, when preserved; e.g., Dryopithecus (Begun, 1994, 2002; Kordos & Begun, 1997). A deep fossa is also present in H. sapiens. Glenoid fossa depth is variable (= 1) in H. ergaster (Strait et al., 1997; Strait & Grine, 2001). The glenoid fossa is of intermediate depth (= 2) in Pongo, Gorilla, K. platyops, K. rudolfensis, Australopithecus, P. robustus, and H. habilis (B.A. Wood, 1991; Strait & Grine, 2001; M.G. Leakey et al., 2001). Sahelanthropus is described as having a shallow glenoid fossa, similar to the condition observed in Pan (= 3) (T.D. White et al., 1994; Strait et al., 1997; Brunet et al., 2002). The same applies to Ardipithecus, members of the "anamensis group," Praeanthropus, and P walkeri (Strait & Grine, 2001).

0 0

Post a comment