A review of the systematics and taxonomy of hominoidea: history, morphology, molecules, and fossils

The history of hominoid systematics reveals a general tendency to recognize diversity in the fossil record of “apes” and “basal hominoids,” but a view toward taxonomic limitation with regard to hominids, which was exacerbated in the 1980s by the “removal” of fossils such as Sivapithecus (=Ramapithecus) and their association via morphological synapomorphy with Pongo. The latter, in turn, reinforced the increasingly accepted, molecularly based theory of human-African ape relatedness, which was never substantially supported by morphology. Although claims to being cladistic in associating humans with the African apes (or Pan alone) abound in the literature, molecularly and morphologically based analyses are, however, not only procedurally different, they identify synapomorphy differently. Continuing confusion of orangutan-like specimens as hominids plus recent re-evaluations of diversity in the human fossil record as well new discoveries of so-called basal fossil hominoids argue for a broadening of hominoid classification until such time as the clades and the relationships between and within them become better understood. Key words: Systematics, hominoid, hominid, synapomorphy, orangutan clade, molecules versus morphology, regulatory genes.