Editing Lung (section)

== Evolutionary origins ==
The lungs of today's terrestrial [[vertebrate]]s and the [[gas bladder]]s of today's [[fish]] are believed to have evolved from simple sacs, as outpocketings of the [[esophagus|oesophagus]], that allowed early fish to gulp air under oxygen-poor conditions.<ref name=farmer>{{Cite journal |title=Did lungs and the intracardiac shunt evolve to oxygenate the heart in vertebrates |author=Colleen Farmer |journal=Paleobiology |year=1997 |url=http://www.biology.utah.edu/farmer/publications%20pdf/1997%20Paleobiology23.pdf |doi=10.1017/S0094837300019734 |volume=23 |pages=358–372 |issue=3 |bibcode=1997Pbio...23..358F |s2cid=87285937 |url-status=dead |archive-url=https://web.archive.org/web/20100611170942/http://www.biology.utah.edu/farmer/publications%20pdf/1997%20Paleobiology23.pdf |archive-date=2010-06-11 }}</ref> These outpocketings first arose in the  [[Osteichthyes|bony fish]]. In most of the [[Actinopterygii|ray-finned fish]], the sacs evolved into closed off gas bladders, while a number of [[carp]], [[trout]], [[herring]], [[catfish]], and [[eel]]s have retained the [[physostome]] condition with the sac being open to the oesophagus. In more basal bony fish, such as the [[gar]], [[bichir]], [[bowfin]] and the [[Sarcopterygii|lobe-finned fish]], the bladders have evolved to primarily function as lungs.<ref name="farmer" /> The lobe-finned fish gave rise to the land-based [[tetrapod]]s. Thus, the lungs of vertebrates are [[homology (biology)|homologous]] to the gas bladders of fish (but not to their [[gill]]s).<ref>{{cite journal|last1=Longo|first1=Sarah|last2=Riccio|first2=Mark|last3=McCune|first3=Amy R|author3-link=Amy McCune|title=Homology of lungs and gas bladders: Insights from arterial vasculature|journal=Journal of Morphology|date=June 2013|volume=274|issue=6|pages=687–703|doi=10.1002/jmor.20128|pmid=23378277|s2cid=29995935}}</ref>