The respiratory system, broadly considered at molecular, cellular, tissue, and organ levels, constrains the physiological potential of all vertebrates. Not only does this pertain to the fundamental issue of gas exchange and the establishment of a metabolic spectrum among organisms, but respiratory potential dictates virtually all life history characteristics known to partition organisms into their respective ecological and evolutionary niches. From reproductive biology and activity patterns (diurnality vs. nocturnality) to locomotor energetics (sprint vs. sitand-wait predators) and limits on absolute body size, respiratory physiology and anatomy play crucial roles for delimiting the diversity of approaches organisms have used for exploiting their environments.
Recent advances in collecting and integrating datasets derived from extant and fossil taxa have prompted a resurgence in investigations aimed at detailing the evolutionary sequence by which major adaptations have influenced the diversification of amniote groups. Broad-based comparative and functional studies of pulmonary anatomy and ventilatory kinematics of extant sauropsids, integrated with information from an ever-growing body of fossils, have formed the basis for a number of hypotheses regarding the form, function, and evolution of the respiratory apparatus in such diverse groups as turtles, lizards, crocodiles, dinosaurs, pterosaurs, and birds.
Contributions to this issue of The Journal of Experimental Zoology Part A come from a symposium convened at the Eighth International Congress of Vertebrate Morphology held in Paris, France in July 2007. The symposium, entitled