Tympanic Shape

As discussed by Strait et al. (1997), the shape of the tympanic canal and the orientation of the anterior tympanic plate should be considered a single feature because a tubular tympanic will always be associated with a horizontal plate (= 0), while a vertical plate cannot exist without a crest (= 1) (Strait et al., 1997; Strait & Grine, 2001; see also Keyser, 2000). The primitive condition of a tubular tympanic (= 0) is observed in Pongo, Gorilla, and Pan. Sahelanthropus, Ardipithecus, the "anamensis group," Praeanthropus, and K. platyops, are described as tubular lacking a crest, similar to that observed in Ardipithecus; thus, it has the primitive hominid condition (T.D. White et al., 1994; Strait et al., 1997; M.G. Leakey et al., 1995, 2001; Strait & Grine, 2001; Ward et al., 2001; Brunet et al., 2002). They also describe the "1470 group" (K. rudolfensis) as having the same condition in Table 2, though they give no additional information. All other hominids preserving this morphology have a crest with a vertical plate (= 1), although in

P. boisei, the crest and plate are inclined (= 2) (see Kordos & Begun, 1997; Strait et al., 1997; Strait & Grine, 2001).

0 0

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