Archipterygium theory

Archipterygium (or ancient fin) is the concept of a primitive limb from which the limbs of tetrapod animals evolved. The idea was proposed by Carl Gegenbaur in 1878, sometimes termed the gill septum hypothesis and it consisted of a series of rays, one ray large with the remaining small ones attached to the sides of the large one. Gegenbaur based this idea on the fin of Ceratodus and its similarity to the gill-region in Elasmobranchs. He suggested that the pentadactyl limb of modern tetrapods was derived from one side of the archipterygium. Thomas Huxley examined the idea and argued against it. He suggested that the tetrapod limb or cheiropterygium differed in its origins from that of the lungfish and that the two may have diversified from a true ancestral archipterygium.{{cite journal|doi=10.2307/2408744|jstor=2408744|title=Radial Condensation in the Axis of the Evolving Limb|journal=Evolution|volume=39|issue=5|pages=1159–1163|year=1985|last1=Stephens|first1=Trent D.|last2=Strecker|first2=Teresa R.|pmid=28561510}}{{cite book| title=Fins into Limbs: Evolution, Development, and Transformation| editor=Hall, Brian K.| publisher=University of Chicago Press| year=2008}} An alternate origin for tetrapod limbs was identified in the lateral fins by Francis Balfour.{{cite journal| title=The evolutionary history of the vertebrate limb|author=Kerr, J. Graham| journal=Science Progress in the Twentieth Century| volume=18| issue=70| year=1923| pages= 257–266 }} These were followed by several other modified hypotheses.{{Cite journal| volume = 1994| issue = Supplement| pages = 169–180| last = Coates| first = Michael I.| title = The origin of vertebrate limbs| journal = Development| date = 1994-01-01| doi = 10.1242/dev.1994.Supplement.169|url=http://dev.biologists.org/content/develop/1994/Supplement/169.full.pdf}} Although the idea of the archipterygium is outdated, it was one of the first major applications of evolutionary morphology and development.{{cite journal|doi=10.1002/dvdy.21268|pmid=17676641|title=Insights from sharks: Evolutionary and developmental models of fin development|journal=Developmental Dynamics|volume=236|issue=9|pages=2421–2431|year=2007|last1=Cole|first1=Nicholas J.|last2=Currie|first2=Peter D.|s2cid=40763215|doi-access=free}}{{cite journal|doi= 10.1073/pnas.1403665112|title= Organogenesis in deep time: A problem in genomics, development, and paleontology|journal= Proceedings of the National Academy of Sciences|volume= 112|issue= 16|pages= 4871–4876|year= 2015|last1= Pieretti|first1= Joyce|last2= Gehrke|first2= Andrew R.|last3= Schneider|first3= Igor|last4= Adachi|first4= Noritaka|last5= Nakamura|first5= Tetsuya|last6= Shubin|first6= Neil H.|pmid=25901307|pmc=4413340|bibcode= 2015PNAS..112.4871P|doi-access= free}}{{cite journal|doi=10.1078/1431-7613-00087|title=The Evolution of Paired Fins|journal=Theory in Biosciences|volume=122|issue=2–3|pages=266–287|year=2003|last1=Coates|first1=M}}