The living dinosaur: accomplishments and challenges of reconstructing dinosaur physiology.

The drive to determine the physiology of non-avian dinosaurs has produced several novel methodologies. In this review, we survey the current state of the field and evaluate the latest reconstructions of non-avian dinosaurian metabolism, thermoregulation, respiratory biology, and the cardiovascular and digestive systems. Most inferences of dinosaur physiology are based on correlations that assume tightly linked relationships between physiology and anatomy. Such causal links must first be well established, tested and functionally validated across a phylogenetically broad range of extant taxa before they can be applied to extinct forms. We offer some basic guidelines for conducting evidence-based, robust reconstructions of palaeophysiology that stay within the confines of both empirical studies and the fossil record.