Palaeontology Department Seminar
Taking a deep breath: bones, air sacs and the evolution of archosaur respiratory systems
Dr. Paul Barrett, Department of Palaeontology, NHM
Thursday 12th April
Neil Chalmers Seminar Room, DC2,
Birds have highly specialised respiratory systems that involve unidirectional movement of air through stiff, small lungs and a complex system of associated air sacs. These air sacs invade many postcranial skeletal elements during development, leaving characteristic traces. Similar features are present in many saurischian dinosaurs, and it seems likely that the accompanying soft-tissue features were present in these animals too. More vexed is the question of how ancient these features are and whether they had a wider distribution among archosaurs. A survey of numerous extinct and extant archosaurs shows unambiguous evidence for an ancient origin of these bird-like features, with their presence in many bird-line archosaurs. The possession of air sacs in crocodile-line archosaurs is more difficult to determine, but some features of the bony anatomy, and recently published work on the physiology of living crocodiles, suggests that many features formerly considered to be unique to birds actually had a much wider distribution. This has several interesting implications for the evolution of activity levels and locomotion in both bird- and croc-line archosaurs.
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