Data from: Palaeohistological evidence for ancestral high metabolic rate in archosaurs

Metabolic heat production in archosaurs has played an important role in
their evolutionary radiation during the Mesozoic, and their ancestral
metabolic condition has long been a matter of debate in systematics and
palaeontology. The study of fossil bone histology provides crucial
information on bone growth rate, which has been used to indirectly
investigate the evolution of thermometabolism in archosaurs. However, no
quantitative estimation of metabolic rate has ever been performed on
fossils using bone histological features. Moreover, to date, no inference
model has included phylogenetic information in the form of predictive
variables. Here we performed statistical predictive modelling using the
new method of phylogenetic eigenvector maps on a set of bone histological
features for a sample of extant and extinct vertebrates, in order to
estimate metabolic rates of fossil archosauromorphs. This modelling
procedure serves as a case study for eigenvector-based predictive
modelling in a phylogenetic context, as well as an investigation of the
poorly known evolutionary patterns of metabolic rate in archosaurs. Our
results show that Mesozoic theropod dinosaurs exhibit metabolic rates very
close to those found in modern birds, that archosaurs share an higher
ancestral metabolic rate than that of extant ectotherms, and that this
derived high metabolic rate was acquired at a much more inclusive level of
the phylogenetic tree, among non-archosaurian archosauromorphs. These
results also highlight the difficulties of assigning a given heat
production strategy (i.e. endothermy, ectothermy) to an estimated
metabolic rate value, and confirm findings of previous studies that the
definition of the endotherm/ectotherm dichotomy may be ambiguous.