Neornithes Gadow, 1893 - living birds Neognathae Pycraft 1900 see Cohort Neognathae Pycraft, 1900 Neoaves Sibley et al. 1988 see Subcohort Neoaves Sibley et al., 1988 Family Opisthocomidae Swainson, 1837 [monotypic] - hoatzins 1 Genus Opisthocomus Illiger, 1811 [monotypic]