There is far more to dinosaurs than just their impressive appearance in museum displays and fearsome demeanor in movies. In many respects they were probably the most successful of all the land vertebrates. Their 150+ million year cosmopolitan reign over the terrestrial environment (from the Late Triassic to the Late Cretaceous) far exceeds the magnitude of dominance by any other group of tetrapods, including the mammals and their ancestors. Dinosaurian diversity was spectacular and their variety encompassed some of the most specialized herbivores and carnivores ever to have existed. Little wonder that so much energy has been devoted to understanding the biology of these long extinct reptiles. No other aspect of dinosaur biology has sparked more interest or controversy than have attempts to decipher their metabolic status. The currently popular notion that dinosaurs may, like living mammals and birds, have been endothermic (or "warm-blooded") provides a model that reinforces the interpretation of these animals as having led particularly active, interesting lives. The traditional alternative, that dinosaurs were ectotherms (or "cold-blooded"), is conventionally, albeit mistakenly, associated with unintelligent brutes leading sluggish, sedentary lives. Fortunately, recent discoveries have provided exciting new insight into the subject. Respiratory turbinates are bony or cartilaginous structures located in the nasal passage of all living terrestrial endotherms (birds and mammals). They function to reduce respiratory heat and water loss and are absent in all cold blooded vertebrates. The PIs propose to look for evidence for the presence, or absence, of respiratory turbinates in a variety of dinosaurs, including the meat-eating dinosaurs as well as in the great assemblage of the ornithischians, or herbivorous, dinosaurs. Additionally, information about rib/lung morphology in dinosaurs is likely to provide insight into the activity capacity of these animals. Given the distinct rib/sternal features associated with ventilation of the lung in living birds and mammals, it seems likely that dinosaur lung structure can be at least approximated by a careful examination of axial skeletal elements in fossils of these animals. Accordingly, it is proposed to undertake an examination of dinosaur axial skeletal structure with a view toward a reasonable, data-based reconstruction of the theropod lung.
