Editing Tetrapod (section)

==== Recoil aspiration ====
Although tetrapods are widely thought to have inhaled through buccal pumping (mouth pumping), according to an alternative hypothesis, aspiration (inhalation) occurred through passive recoil of the [[exoskeleton]] in a manner similar to the contemporary primitive ray-finned fish ''[[Polypterus]]''. This fish inhales through its [[Spiracle (vertebrates)|spiracle]] (blowhole), an anatomical feature present in early tetrapods. Exhalation is powered by muscles in the torso. During exhalation, the bony scales in the upper chest region become indented. When the muscles are relaxed, the bony scales spring back into position, generating considerable negative pressure within the torso, resulting in a very rapid intake of air through the spiracle.<ref name="EvansClaiborne2005">{{cite book|last1=Evans|first1=David H.|last2=Claiborne|first2=James B.|title=The Physiology of Fishes, Third Edition|url=https://books.google.com/books?id=lBltoKDaBVEC&pg=PA107|access-date=28 July 2015|date=15 December 2005|publisher=CRC Press|isbn=978-0-8493-2022-4|page=107|archive-date=19 August 2020|archive-url=https://web.archive.org/web/20200819141304/https://books.google.com/books?id=lBltoKDaBVEC&pg=PA107|url-status=live}}</ref><ref name="GrahamWegner2014">{{cite journal|last1=Graham|first1=Jeffrey B.|last2=Wegner|first2=Nicholas C.|last3=Miller|first3=Lauren A.|last4=Jew|first4=Corey J.|last5=Lai|first5=N Chin|last6=Berquist|first6=Rachel M.|last7=Frank|first7=Lawrence R.|last8=Long|first8=John A.|title=Spiracular air breathing in polypterid fishes and its implications for aerial respiration in stem tetrapods|journal=Nature Communications|volume=5|date=January 2014|url=https://www.researchgate.net/publication/259875906|issn=2041-1723|doi=10.1038/ncomms4022|pmid=24451680|page=3022|bibcode=2014NatCo...5.3022G|doi-access=free|access-date=2018-11-24|archive-date=2020-09-04|archive-url=https://web.archive.org/web/20200904221941/https://www.researchgate.net/publication/259875906_Spiracular_air_breathing_in_polypterid_fishes_and_its_implications_for_aerial_respiration_in_stem_tetrapods|url-status=live}}</ref><ref name="VickaryousSire2009">{{cite journal|last1=Vickaryous|first1=Matthew K.|last2=Sire|first2=Jean-Yves|title=The integumentary skeleton of tetrapods: origin, evolution, and development|journal=Journal of Anatomy|volume=214|issue=4|date=April 2009|pages=441–464|issn=0021-8782|doi=10.1111/j.1469-7580.2008.01043.x|pmid=19422424|pmc=2736118}}</ref>