9420290 William J. Hillenius Endmthermy, or "warm-bloodedness" was a significant innovation in animal evolution. Because most physiological adaptations associated with endothermy occur in soft tissue and do not fossilize, the early evolution of endothermy, including its possible presence among dinosaurs, remains largely speculative. New evidence suggests that the high metabolic rates and lung ventilation rates associated with endothermy in mammals require complex bony structures in the nose (respiratory turbinals) that humidify inhaled air and decrease respiratory water loss. This research will test to see whether the same association holds for living birds, and examine fossil birds and their ancestors, the dinosaurs, for evidence of the presence of respiratory turbinals. It will use non-invasive, high-resolution computed X-ray tomography scans to examine the nasal internal anatomy of fossils of birds and representatives of a variety of dinosaur groups. The results will show when endothermy arose during the evolution of birds, and whether and when endothermy evolved in dinosaurs. The research will lead to a greater understanding of the physiology of the dinosaurs, and possibly of the reasons for their extinction.
