Cranial Capacity

While there is some overlap between the ranges used here, allocation is based on recognizing the range within and between differing taxonomic units; and if the upper range is moderately greater (even though there may be overlap at the lower range), we define a separate character state. For example, while both Gorilla and Pan are defined by an upper range of 500 cc (= 0), a separate character state is recognized for a range between 428 and 550 cc (= 1) because the upper range is moderately larger then the upper range observed in the extant hominids (and partially define distinct taxonomic units). Cranial capacities published by Aiello and Dean (1990), Strait et al. (1997), Asfaw et al. (1999), M.G. Leakey et al. (2001), and Brunet et al. (2002) were used to allocate taxa to character states.

Pongo, Gorilla, Pan, Sahelanthropus, Praeanthropus, the "garhi group," K. playops, and P walkeri are all defined by relatively small cranial capacities, less than 500 cc (= 0). Next are Australopithecus, P. boisei, and P robustus, with a capacity between 428 and 550 cc (= 1). This is followed by H. habilis, with a capacity between 509 and 675 cc (= 2). Kenyanthropus rudolfensis and H. ergaster are defined by a capacity between 750 and 1,100 cc (= 3), while H. sapiens is defined by a capacity larger than 1100 cc (= 4).

0 0

Post a comment