7 The Species and Diversity of Australopiths

摘要: In this chapter, the historical, systematic, and anatomical evidence for diversity of species within australopith grade is reviewed. Given a strict evolutionary definition, nominal taxonomic species‐lineage do not necessarily map onto one another in fossil record. Species‐lineages entail statements ancestry descent that depend on consistency phylogenetic stratophenetic data. The requirements identifying species‐lineages record are severe, early hominin rarely met, most often owing to small sample size, under‐ represented character data, nonrepresentation rare or short‐lived taxa, poor chronological resolution, gaps time‐stratigraphic framework, some combination these factors. Because hypotheses concerning ‘‘bushiness’’ tree identification lineages, phenteically based ‘‘paleospecies,’’ confidence with respect issue justified majority There two cases which an approach question can be attempted. one, consistent evolution Australopithecus anamensis into A. afarensis via anagenesis. other, boisei, likely entailed speciation event gave rise southern African clade (represented by robustus) subsequent appearance aethiopicus. late Pliocene time period latter events transpired (ca. 2.8‐2.3 Ma) substantial morphologicial diversity, high probability synchronicity among known samples. Although it possible connect taxa (A. aethiopicus, africanus, garhi) particular descendants due defects data base, probably documents previously (and subsequently) unmatched degree lineage proliferation compared other parts human challenge paleoanthropologists devote resources improving part then create testable adaptive explain it.