Monophyly and phylogeny of cuckoos (Aves, Cuculidae) inferred from osteological characters

A reanalysis of 32 characters from the literature previously deemed diagnos tic of the Cuculidae revealed only five to be synapomorphic. I subsequently examined skeletons from 54 avian families and identified nine additional s ynapomorphies that supported cuckoo monophyly. My cladistic analysis of 33 cuculid genera using 135 skeletal characters differs markedly from currentl y accepted taxonomies. The most striking deviation is the placement of both New and Old World parasitic cuckoos in the Cuculinae, supporting tie evolu tion of brood parasitism in a single event rather than three times as previ ously proposed. Unlike earlier classifications, the Cuculinae also includes the facultative parasites Coccyzus. This suggests that the ancestral Coccy zus was an obligate parasite, and is consistent with the many behavioral ad aptations to parasitism exhibited by this genus. Other changes include the placement of three subfamilies, comprising non-parasitic, terrestrial cucko os of Old World (Centropodinae and Carpococcystinae) and New World (Neomorp hinae) distribution, in basal positions on the tree. Nineteen characters su pport a sister relationship between the Hoatzin (Opisthocomus hoatzin Mulle r) and turacos (Musophagidae), and not cuckoos. Three synapomorphies of the os carpi ulnare were found to unite the Cuculidae, turacos, and the Hoatzi n, suggesting that these three diverse taxa may constitute a monophyletic g roup. (C) 2000 The Linnean Society of London.