The feature refers to the expansion (increased osteoblast activity) of the bone table within the region of asterion (Kimbel & Rak, 1985). This results in a partial overlap of the temporal, parietal, and occipital bones (Strait et al., 1997). This feature is included because of its association with nuchal and masticatory stress (Kimbel & Rak, 1985), which are of functional interest and also likely to be of phylogenetic significance, given the concept of phylogenetic niche conservatism (see text). Also, because of the complex interplay of sutural and bone growth patterns associated with the development of this feature, we suggest it is likely to have a strong heri-tability factor (see partly Enlow & Hans, 1996). Only in the East African species of Paranthropus has this phenotypic feature been expressed to varying degrees, and in some specimens of P. boisei, it is absent altogether; e.g. KNM-ER 23000 (B. Brown et al., 1993).
Was this article helpful?