Fig. 1

Time-calibrated phylogeny of taxa sampled in the study. Maximum clade credibility tree based on Jetz et al. [26] with a Hackett et al. [28] backbone. Non-avian dinosaurs and Archaeopteryx were incorporated into the phylogeny based on fossil occurrence data from Paleobiology Database (paleobiodb.org). Colors correspond to major clades and are consistent across figures. Red crosses next to taxonomic names indicate a flightless taxon