= Passeriformes
{c}
<Passeriformes> is the order of <birds> commonly called passerines or perching birds. Its major living branches include <Acanthisittidae>, the New Zealand wrens; <Tyranni>, the suboscines; and <Passeri>, the <songbirds>. Thus <songbirds> form an important branch within <Passeriformes>, rather than being an exact synonym for the entire order.<Earth history and the passerine superradiation>[Results, three principal passerine lineages]{ref}
The group illustrates how evolutionary histories are tested with independent kinds of evidence. A 2019 study analyzed 4060 nuclear <DNA> regions across 137 passerine families and used 13 <fossils> to calibrate the resulting <phylogenetic tree>. DNA comparisons estimate relationships and relative amounts of change; a fossil supplies an age constraint, rather than a complete date label for every branch.<Earth history and the passerine superradiation>[Abstract and phylogenetic methods]{ref}
An illustrative consequence is that two visually similar birds need not be closest relatives: similar ways of feeding or moving can favor similar shapes. Conversely, related branches can evolve very different appearances. A well-sampled <phylogenetic tree> lets investigators ask whether a repeated feature was inherited once or arose independently, while making explicit which taxa and <genes> were compared. The 2019 reconstruction tested explanations for diversification instead of assuming that a rise in global temperature must automatically produce a matching rise in speciation.
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