Archipterygium (or ancient fin) is the concept of a primitive limb from which the limbs of tetrapod animals evolved. The idea was proposed by

Karl Gegenbaur Karl Gegenbaur (21 August 1826 – 14 June 1903)"Karl Gegenbaur – Encyclopædia Britannica" (biography), ''Encyclopædia Britannica'', 2006, Britannica.coBritannica-KarlG was a German anatomist and professor who demonstrated that the field of c ...

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 ''Ceratodus'' (from el, κέρας , 'horn' and el, ὀδούς 'tooth') was a wide-ranging genus of extinct lungfish. Fossil evidence dates back to the Early Triassic. A wide range of fossil species from different time periods have been found ...

'' 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 Thomas Henry Huxley (4 May 1825 – 29 June 1895) was an English biologist and anthropologist specialising in comparative anatomy. He has become known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution. The stor ...

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. An alternate origin for tetrapod limbs was identified in the lateral fins by Francis Balfour. These were followed by several other modified hypotheses. Although the idea of the archipterygium is outdated, it was one of the first major applications of evolutionary morphology and development.

References

{{reflist Evolution by phenotype

See also

References