Asterionic Notch

This character cannot be considered totally integrated with the two previous characters discussed above (9 and 10) because a number of taxa that do not express these morphologies are characterized by an asterionic notch. This feature is defined by the inferoposterior intrusion of the parietal between the occipital and the mastoid portion of the temporal bones (Kimbel & Rak, 1985; Aiello & Dean, 1990). This feature has been associated with the development and configuration of the temporalis muscle (Robinson, 1958; Tobias, 1967; Jolly, 1970; Kimbel et al., 1984). Pongo, Gorilla Pan, Praeanthropus, and P walkeri are all defined by the presence of an asterionic notch (= 0) (Kimbel & Rak, 1985; Walker et al., 1986; Walker & Leakey, 1988). The condition observed in H. habilis is said to be variable (= 1), while all other taxa preserving this region lack an asterionic notch (= 2) (Kimble & Rak, 1985; Skelton & McHenry, 1992; Strait et al., 1997; Strait & Grine, 2001).

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