Out of Gondwana: the origin of passerine birds

Two recent papers analysing nuclear DNA sequence data shed new light on the origin of perching birds (Passeriformes) and the structure of their radiation. Both papers find that the New Zealand wrens Acanthisitta fall at the base of the passerine radiation, implying an origin of this clade in Gondwana. Additionally, among oscine passerines (songbirds), both papers fail to support a sister group relationship between the largely Australo–Papuan Corvida and the Afro–Eurasian Passerida, as outlined in Sibley and Ahlquist’s tapestry. Rather, they converge on a phylogeny in which the Passerida is nested within the Corvida, suggesting an origin of songbirds in eastern Gondwana (Australia plus New Guinea). Finally, a Cretaceous origin of passerine birds is supported by the new data, albeit more on grounds of biogeography than of molecular clocks. The new papers solidify a synthesis of paleontological, phylogenetic and molecular data that has been growing over the past decade, and pave the way for a new generation of comparative studies of passerines.