Data from: Diet evolution and body temperature in tetrapods: cool old carnivores and hot young herbivores

Diet is a key aspect of life in animals. There have been numerous origins of herbivory across animals, but the factors that explain these origins remain poorly understood. One potentially crucial factor is body temperature (T_b), since the gut-dwelling bacteria that help digest cellulose in many herbivores are thought to require high temperatures. However, analyses in birds, lizards, and mammals found only limited evidence for higher T_b in herbivores than carnivores. Those previous analyses tested whether diet explains T_b evolution, and not whether T_b explains diet evolution. Here, we used phylogenetic methods to test whether T_b helps explain diet evolution across tetrapods. We analyzed 1712 species with matched data on diet, T_b, and phylogeny. We also include body size and diel activity. Ancestral reconstructions indicated that tetrapods likely had a carnivorous ancestor, followed by repeated transitions to omnivory and herbivory, especially in the last 110 million years (i.e. when angiosperms came to dominate plant communities). Thus, extant herbivorous lineages in tetrapods are relatively young, in contrast to many older carnivorous lineages. They are also relatively unstable, since reversals from herbivory to omnivory and from omnivory to carnivory were as frequent as gains of herbivory and omnivory. Using phylogenetic logistic regression (and other methods), we generally support the hypothesis that higher T_b helps explain the evolution of herbivory across tetrapods and within birds, mammals, lepidosaurs, and turtles. Phylogenetic path analyses suggest that T_bgenerally drives the evolution of herbivory, and not vice versa. Our analyses also suggest that T_b may be more important for the evolution of herbivory than large body size or diurnal diel activity, both of which are significant predictors of herbivory in some cases.