To better determine the history of modern birds, we performed a genome-scale phylogenetic analysis of 48 species representing all orders of Neoaves using phylogenomic methods created to handle genome-scale data. We recovered a highly resolved tree that confirms previously controversial sister or close relationships. We identified the first divergence in Neoaves, two groups we named Passerea and Columbea, representing independent lineages of diverse and convergently evolved land and water bird species. Among Passerea, we infer the common ancestor of core landbirds to have been an apex predator and confirm independent gains of vocal learning. Among Columbea, we identify pigeons and flamingoes as belonging to sister clades. Even with whole genomes, some of the earliest branches in Neoaves proved challenging to resolve, which was best explained by massive protein-coding sequence convergence and high levels of incomplete lineage sorting that occurred during a rapid radiation after the Cretaceous-Paleogene mass extinction event about 66 million years ago.

Deep avian evolutionary relationships have been difficult to resolve as a result of a putative explosive radiation. Our study examined approximately 32 kilobases of aligned nuclear DNA sequences from 19 independent loci for 169 species, representing all major extant groups, and recovered a robust phylogeny from a genome-wide signal supported by multiple analytical methods. We documented well-supported, previously unrecognized interordinal relationships (such as a sister relationship between passerines and parrots) and corroborated previously contentious groupings (such as flamingos and grebes). Our conclusions challenge current classifications and alter our understanding of trait evolution; for example, some diurnal birds evolved from nocturnal ancestors. Our results provide a valuable resource for phylogenetic and comparative studies in birds.