Early hominid masticatory characters are widely considered to be more prone to 
homoplasy than characters from other regions of the early hominid skull and 
therefore less reliable for phylogenetic reconstruction. This hypothesis has 
important implications for current reconstructions of early hominid phylogeny, 
but it has never been tested. In this paper we evaluate the likely veracity of 
the hypothesis using craniometric data from extant primate groups for which 
reliable consensus molecular phylogenies are available. Datasets representing 
the extant large-bodied hominoid genera and the extant papionin genera were 
compiled from standard measurements. The data were adjusted to minimise the 
confounding effects of body size, and then converted into discrete character 
states using divergence coding. Each dataset was divided into four regional 
character groups: (1) palate and upper dentition, (2) mandible and lower 
dentition, (3) face and (4) cranial vault and base. Thereafter, the regional 
character groups were analysed using cladistic methods and the resulting 
phylogenetic hypotheses judged against the consensus molecular phylogenies for 
the hominoids and papionins. The analyses indicated that the regions dominated 
by masticatory characters-the palate and upper dentition, and the mandible and 
lower dentition-are no less reliable for phylogenetic reconstruction than the 
other regions of the skull. The four regions were equally affected by homoplasy 
and were, therefore, equally unreliable for phylogenetic reconstruction. This 
finding challenges the recent suggestion that Paranthropus is polyphyletic, 
which is based on the assumption that masticatory characters are especially 
prone to homoplasy. Our finding also suggests that, contrary to current 
practice, there is no a priori reason to de-emphasise the phylogenetic 
significance of the masticatory similarities between Homo rudolfensis and the 
australopiths. The corollary of this is that H. rudolfensis is unlikely to be a 
member of the Homo clade and should therefore be allocated to another genus.