Air sac - Wikipedia
Air sacs are spaces within an organism where there is the constant presence of air. Among modern animals, birds possess the most air sacs (9–11), with their extinct dinosaurian relatives showing a great increase[clarification needed ] in the pneumatization (presence of air) in their bones.[ 1] Birds use air sacs for respiration as well as a number of other things.[ 2] [clarification needed ] Theropods, like Aerosteon, have many air sacs in the body that are not just in bones, and they can be identified as the more primitive form of modern bird airways.[ 3] [clarification needed ] Sauropods are well known for the large number of air pockets in their bones (especially vertebra), although one theropod, Deinocheirus, shows a rivalling number of air pockets.[ 4] [ 5]
Birds have a system of air sacs in their ventilation system.[ 2] The air sacs work to produce a unidirectional flow where air enters and exits the lung at the same rate, contrasting the lungs of other tetrapods such as mammals where air enters and exits the lung in a tidal ventilation.[ 2]
.avif)
