The Lower Eocene Green River Formation has yielded a large number of hitherto mostly undescribed birds. In this study, I describe a new species and genus as the first representative of Zygodactylidae from the New World. Furthermore, new specimens are referred to Gallinuloides wyomingensis (Galliformes), Messelornis nearctica (Gruiformes), and "Neanis" kistneri (?Galbulae). Based on the new specimens, I reveal additional information on the osteology and the systematic affinities of these species. The new specimens corroborate the fact that there is a strong similarity between the Green River avifauna and that of the roughly contemporaneous avifauna of Messel (Germany). In both sites, Messelornithidae and small arboreal birds are predominant in the fossil record.