Comparative timing of divergences for avian orders and families based on four different 'relaxed clock' methods. Chronograms based on the optimal mtDNA tree reconstruction (TOptimal) using r8s (top left), Dating5 (bottom left), PATHd8 (top right) and Multidivtime (bottom right); see methods for explanation of differences between analytical approaches. For legibility, error bars are removed and trees are pruned to the family level. Filled circles denote major clades: orange, Paleognathae; purple, Neognathae; blue, Galloanserae; green, Neoaves; red, Passeriformes. Time is given in millions of years before present. The vertical dashed lines indicate the K-Pg boundary. r8s, Dating5 and Multidivtime reconstructions support Cretaceous origin and diversification. PATHd8 alone supports Cretaceous origin but Tertiary diversification.
Brown et al. BMC Biology 2008 6:6 doi:10.1186/1741-7007-6-6