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Unidirectional gator breathing in Science
Saw this presented at SICB a few years ago - super cool stuff!
Farmer, C.G., and K. Sanders. 2010. Unidirectional airflow in the
lungs of alligators. Science 327(5963):338-340.
The lungs of birds move air in only one direction during both
inspiration and expiration through most of the tubular gas-exchanging
bronchi (parabronchi), whereas in the lungs of mammals and presumably
other vertebrates, air moves tidally into and out of terminal
gas-exchange structures, which are cul-de-sacs. Unidirectional flow
purportedly depends on bellowslike ventilation by air sacs and may
have evolved to meet the high aerobic demands of sustained flight.
Here, we show that air flows unidirectionally through parabronchi in
the lungs of the American alligator, an amphibious ectotherm without
air sacs, which suggests that this pattern dates back to the basal
archosaurs of the Triassic and may have been present in their
nondinosaur descendants (phytosaurs, aetosaurs, rauisuchians,
crocodylomorphs, and pterosaurs) as well as in dinosaurs.