TOTAL-EVIDENCE ANALYSES SUPPORT A CRETACEOUS ORIGIN OF TELLURAVES

Despite a vast accumulation of molecular data, the timing of diversification of the modern bird lineages has remained elusive. The origination of Telluraves—a range of principally arboreal species—is especially controversial, as it contains the most species rich avian group, the passerines. Estimates for the origination of Telluraves vary widely, but paleontological studies generally suggest a very young, post-K-Pg, origination, while neontological studies find older, Cretaceous, origins. Here, we employ total-evidence dating to help provide estimates of divergence times that are expected to be both less sensitive to prior assumptions and probably more accurate. Specifically, we use a large collection of morphological character data from arboreal bird fossils, along with combined molecular sequence and morphological character data from extant taxa. The results suggest a Late Cretaceous origin for Telluraves, preceding the K-Pg boundary, with much of the subsequent diversification most likely occurring in the Tertiary. Contrary to most previous studies, we recover very little confidence for the precise placement of many fossil species, possibly due to rapid diversification, paucity of character data, and rapid morphological differentiation during the early history of the group.