Taxonomical reappraisal of Cathayornithidae (Aves: Enantiornithes)

A complete redescription of <i>Cathayornis caudatus</i> Hou, 1997 is provided based on new information from a resin cast of the holotype, leading to reinterpretation of many morphological features of this initially poorly diagnosed taxon. Detailed comparisons across various specimens referred to Cathayornithidae Zhou <i>et al.</i>, 1992 indicate that <i>Sinornis santensis</i>, <i>Cathayornis yandica</i>, <i>C. caudatus</i> and <i>Eocathayornis walkeri</i> are valid taxa, but that <i>C. chabuensis</i> should be regarded as a <i>nomen dubium</i>. The holotype and referred specimens of <i>C. chabuensis</i> differ significantly in morphology, indicating that they do not belong to the same species. A comprehensive phylogenetic analysis targeted at Mesozoic birds reveals that neither Cathayornithidae Zhou <i>et al.</i>, 1992 nor <i>Cathayornis</i> Zhou <i>et al.</i>, 1992 are monophyletic, and that <i>C. yandica</i> can be regarded as the only species in a monospecific Cathayornithidae. The holotype of ‘<i>C. caudatus</i>’ is assigned to the genus <i>Houornis</i> gen. nov., and a taxonomic reassessment of other ‘cathayornithids’ is presented. http://zoobank.org/urn:lsid:zoobank.org:pub:0B1A404A-CC6A-4609-8CC5-C0DD62983C9A