Mass estimation of extinct taxa and phylogenetic hypotheses both influence analyses of character evolution in a large clade of birds (Telluraves).

Incorporating extinct taxa in phylogenetic comparative methods is rapidly becoming invaluable in studies of character evolution. An increasing number of studies have evaluated the effects of extinct taxa, and different numbers of extinct taxa, on model selection and parameter estimation. Body mass is a well-studied phenotype, but individual mass estimates may vary dramatically depending on the particular measurement used. Here, we perform an analysis of body mass evolution in a large clade of principally arboreal birds, incorporating 76 extinct species. We evaluate how different methods for estimating body mass of extinct taxa, and different phylogenetic hypotheses, affect our understanding of the rate and pattern of body mass evolution. Our results show that model selection can vary dramatically depending on the phenotypic and phylogenetic hypothesis used in the reconstruction. Even small changes in phenotype estimates can lead to different model selection and, as a result, affect the inferred evolutionary history. The best-fit models support an increase in the rate of evolution following the K-Pg boundary, with variation accumulating linearly through the Cenozoic. These results provide additional insight into the application of comparative models of evolution, as well as the evolutionary history of one of the most spectacular vertebrate radiations.