'Alligator breath'

One of the remarkable features of birds is unidirectional breathing: fresh air enters the lungs both when they breathe in and when they breathe out. This means they get twice as much benefit from each cycle as mammals. It is one of the characteristics that allows many of them to be extremely active with small and light lungs (short explanation here).

C. G. Farmer and Kent Sanders report the same system in Alligators and say the observation suggests that this breathing pattern dates back to the basal archosaurs of the Triassic and their descendants, including both dinosaurs and pterosaurs.


Speaking an outsider/know-next-to-nothing, I think it has long been assumed that pterosaurs would only have been capable of flight if they had a unidirectional breathing system. The new site pterosaur.net has a little information about this (under anatomy).

Image of Preondactylus bufarinii by Mark Witton.