Systematics and Phylogeny
The Passerida quite certainly consist of the 3 major subclades outlined by Sibley & Ahlquist (1990). However, their content has been much revised. In addition, it has turned out that not all passeridan lineages neatly fit into this arrangement. The kinglets are so distinct that they might actually form a separate infraorder, as they are only slightly less basal than the Corvoidea or the Picathartidae. See Jønsson & Fjeldså (2006) for details on phylogeny.
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