This character has been taken from M.G. Leakey et al. (2001). Their Figure 3 indicates three patterns of subnasal prognathism as measured by the angulation of the nasal clivus (prosthion-nasospinale). This character is of interest not only because it relates to subnasal prognathism, but this itself is associated with the requirements of the anterior dentition as well as palate depth, which may be associated with differential patterns of cranial base flexure (see D.E. Lieberman et al., 2001).
Increased prognathism (= 0) is observed in Graecopithecus, Pongo, Gorilla, and Pan, which fall below 30o (= 0). The intermediate condition (= 1) is observed in Dryopithecus, Praeanthropus, Australopithecus, species within Paranthropus, and H. habilis between 30° and 42° (= 1). This also appears to be the case for B0U-VP-12/130 ("garhi group"). Reduced prognathism (= 2) is observed in both species of Kenyanthropus, H. ergaster, and H. sapiens, with reduced prognathism at above 42° (= 0). Sahelanthropus is characterized by weak subnasal prognathism (Brunet et al., 2002), so it is allocated to this character state.
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