Editing Fin (section)

==Evolution==
[[File:Lampanyctodes hectoris (fins).png|thumb|300px|right|{{center|Aquatic animals typically use fins for [[Aquatic locomotion|locomotion]]<br />(1) pectoral fins (paired), (2) pelvic fins (paired), (3) dorsal fin, (4) adipose fin, (5) anal fin, and (6) caudal (tail) fin.}}]]
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 |quote = Aristotle recognised the distinction between [[Analogous structures|analogous]] and [[homologous structures]], and made the following prophetic comparison:
''"Birds in a way resemble fishes. For birds have their wings in the upper part of their bodies and fishes have two fins in the front part of their bodies. Birds have feet on their underpart and most fishes have a second pair of fins in their under-part and near their front fins."''
 |source = – Aristotle, ''[[Progression of Animals|De incessu animalium]]'' <ref>{{cite journal | last1 = Moore | first1 = John A | year = 1988 | title = Understanding nature—form and function | url = http://www.sicb.org/dl/saawok/449.pdf | journal = American Zoologist | volume = 28 | issue = 2 | pages = 449–584 [485] | doi = 10.1093/icb/28.2.449 | doi-access = free | access-date = 2014-11-08 | archive-date = 2015-09-24 | archive-url = https://web.archive.org/web/20150924101610/http://www.sicb.org/dl/saawok/449.pdf | url-status = dead }}</ref>
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There is an old theory, proposed by anatomist [[Carl Gegenbaur]], which has been often disregarded in science textbooks, "that fins and (later) limbs evolved from the gills of an extinct vertebrate". Gaps in the fossil record had not allowed a definitive conclusion. In 2009, researchers from the University of Chicago found evidence that the "genetic architecture of gills, fins and limbs is the same", and that "the skeleton of any appendage off the body of an animal is probably patterned by the developmental genetic program that we have traced back to formation of gills in sharks".<ref>[https://www.sciencedaily.com/releases/2009/03/090323212021.htm Evolution Of Fins And Limbs Linked With That Of Gills] {{Webarchive|url=https://web.archive.org/web/20190530052749/https://www.sciencedaily.com/releases/2009/03/090323212021.htm |date=2019-05-30 }} ''ScienceDaily''. 25 March 2009.</ref><ref>{{cite journal | last1 = Gillis | first1 = JA | last2 = Dahn | first2 = RD | last3 = Shubin | first3 = NH | year = 2009 | title = Shared developmental mechanisms pattern the vertebrate gill arch and paired fin skeletons | journal = Proceedings of the National Academy of Sciences | volume = 106 | issue = 14| pages = 5720–5724 | doi=10.1073/pnas.0810959106 | pmid=19321424 | pmc=2667079 | bibcode = 2009PNAS..106.5720G| doi-access = free }}</ref><ref>[http://www.uctv.tv/shows/Wings-Legs-and-Fins-How-Do-New-Organs-Arise-in-Evolution-16421 Wings, legs, and fins: How do new organs arise in evolution?] {{Webarchive|url=https://web.archive.org/web/20200927104725/http://www.uctv.tv/shows/Wings-Legs-and-Fins-How-Do-New-Organs-Arise-in-Evolution-16421 |date=2020-09-27 }} [[Neil Shubin]], University of Chicago.</ref> Recent studies support the idea that gill arches and paired fins are serially homologous and thus that fins may have evolved from gill tissues.<ref>{{Cite journal|last1=Sleight|first1=Victoria A|last2=Gillis|first2=J Andrew|date=2020-11-17|title=Embryonic origin and serial homology of gill arches and paired fins in the skate, Leucoraja erinacea|journal=eLife|language=en|volume=9|pages=e60635|doi=10.7554/eLife.60635|pmid=33198887|issn=2050-084X|pmc=7671686 |doi-access=free }}</ref>

Fish are the ancestors of all mammals, reptiles, birds and amphibians.<ref>[https://www.sciencedaily.com/releases/2008/09/080922090843.htm "Primordial Fish Had Rudimentary Fingers"] {{Webarchive|url=https://web.archive.org/web/20200927203302/https://www.sciencedaily.com/releases/2008/09/080922090843.htm |date=2020-09-27 }} ''ScienceDaily'', 23 September 2008.</ref> In particular, terrestrial [[tetrapod]]s (four-legged animals) evolved from fish and made their first forays onto land 400 million years ago. They used paired pectoral and pelvic fins for locomotion. The pectoral fins developed into forelegs (arms in the case of humans) and the pelvic fins developed into hind legs.<ref>Hall, Brian K (2007) [https://books.google.com/books?id=Z0YWn5F9sWkC ''Fins into Limbs: Evolution, Development, and Transformation''] University of Chicago Press. {{ISBN|9780226313375}}.</ref> Much of the genetic machinery that builds a walking limb in a tetrapod is already present in the swimming fin of a fish.<ref>[[Neil Shubin|Shubin, Neil]] (2009) [https://books.google.com/books?id=c008kdNwR1cC ''Your inner fish: A journey into the 3.5 billion year history of the human body''] {{Webarchive|url=https://web.archive.org/web/20230317010712/https://books.google.com/books?id=c008kdNwR1cC |date=2023-03-17 }} Vintage Books. {{ISBN|9780307277459}}. [http://www.uctv.tv/search-details.aspx?showID=16412 ''UCTV'' interview] </ref><ref>Clack, Jennifer A (2012) [https://books.google.com/books?id=6Ztrhm8uLQ0C "From fins to feet"] Chapter 6, pages 187–260, ''in:'' ''Gaining Ground, Second Edition: The Origin and Evolution of Tetrapods'', Indiana University Press. {{ISBN|9780253356758}}.</ref>

[[File:Crossopterygii fins tetrapod legs.svg|thumb|180px|left|Comparison between A) the swimming fin of a [[Sarcopterygii|lobe-finned fish]] and B) the walking leg of a [[tetrapod]]. Bones considered to correspond with each other have the same color.]]
[[File:Ichthyosaurus BW.jpg|thumb|right|In a parallel but independent evolution, the ancient reptile ''[[Ichthyosaurus communis]]'' developed fins (or flippers) very similar to fish (or dolphins).]]

In 2011, researchers at [[Monash University]] in Australia used primitive but still living [[lungfish]] "to trace the evolution of pelvic fin muscles to find out how the load-bearing hind limbs of the tetrapods evolved."<ref>[https://www.sciencedaily.com/releases/2011/10/111004180106.htm Lungfish Provides Insight to Life On Land: 'Humans Are Just Modified Fish'] {{Webarchive|url=https://web.archive.org/web/20201111213122/https://www.sciencedaily.com/releases/2011/10/111004180106.htm |date=2020-11-11 }} ''ScienceDaily'', 7 October 2011.</ref><ref>{{cite journal | last1 = Cole | first1 = NJ | last2 = Hall | first2 = TE | last3 = Don | first3 = EK | last4 = Berger | first4 = S | last5 = Boisvert | first5 = CA | display-authors = etal | year = 2011 | title = Development and Evolution of the Muscles of the Pelvic Fin | journal = PLOS Biology | volume = 9 | issue = 10| page = e1001168 | doi = 10.1371/journal.pbio.1001168 | pmid = 21990962 | pmc = 3186808 | doi-access = free }}</ref> Further research at the University of Chicago found bottom-walking lungfishes had already evolved characteristics of the walking gaits of terrestrial tetrapods.<ref>[https://www.sciencedaily.com/releases/2011/12/111212153117.htm A small step for lungfish, a big step for the evolution of walking"] {{Webarchive|url=https://web.archive.org/web/20170703172143/https://www.sciencedaily.com/releases/2011/12/111212153117.htm |date=2017-07-03 }} ''ScienceDaily'', 13 December 2011.</ref><ref>{{cite journal | last1 = King | first1 = HM | last2 = Shubin | first2 = NH | last3 = Coates | first3 = MI | last4 = Hale | first4 = ME | year = 2011 | title = Behavioral evidence for the evolution of walking and bounding before terrestriality in sarcopterygian fishes | journal = Proceedings of the National Academy of Sciences | volume = 108 | issue = 52| pages = 21146–21151 | doi=10.1073/pnas.1118669109 | pmid=22160688 | pmc=3248479 | bibcode = 2011PNAS..10821146K| doi-access = free }}</ref>

In a classic example of [[convergent evolution]], the pectoral limbs of [[pterosaur]]s, [[Origin of avian flight|birds]] and [[Bat wing development|bats]] further evolved along independent paths into flying wings. Even with flying wings there are many similarities with walking legs, and core aspects of the genetic blueprint of the pectoral fin have been retained.<ref>{{cite journal | last1 = Shubin | first1 = N | last2 = Tabin | first2 = C | last3 = Carroll | first3 = S | year = 1997 | title = Fossils, genes and the evolution of animal limbs | url = http://genepath.med.harvard.edu/~tabin/Pdfs/Shubin.pdf | journal = Nature | volume = 388 | issue = 6643 | pages = 639–648 | doi = 10.1038/41710 | pmid = 9262397 | url-status = dead | archive-url = https://web.archive.org/web/20120916105318/http://genepath.med.harvard.edu/~tabin/Pdfs/Shubin.pdf | archive-date = 2012-09-16 | bibcode = 1997Natur.388..639S | s2cid = 2913898 }}</ref><ref>[http://www.ucmp.berkeley.edu/vertebrates/flight/converge.html Vertebrate flight: The three solutions] {{Webarchive|url=https://web.archive.org/web/20121110035749/http://www.ucmp.berkeley.edu/vertebrates/flight/converge.html |date=2012-11-10 }} University of California. Updated 29 September 2005.</ref>

About 200 million years ago the first mammals appeared. A group of these mammals started returning to the sea about 52 million years ago, thus completing a circle. These are the [[cetacean]]s (whales, dolphins and porpoises). Recent DNA analysis suggests that cetaceans evolved from within the [[even-toed ungulate]]s, and that they share a common ancestor with the [[hippopotamus]].<ref name="ScienceNews">{{Cite web|title=Scientists find missing link between the dolphin, whale and its closest relative, the hippo |date=2005-01-25 |access-date=2007-06-18 |url=http://www.sciencenewsdaily.org/story-2806.html |work=Science News Daily |url-status=dead |archive-url=https://web.archive.org/web/20070304214747/http://www.sciencenewsdaily.org/story-2806.html |archive-date=2007-03-04 }}</ref><ref name="DNA">{{Cite journal | title = More DNA support for a Cetacea/Hippopotamidae clade: the blood-clotting protein gene gamma-fibrinogen | author = Gatesy, J. | journal = [[Molecular Biology and Evolution]] | volume = 14 | pages = 537–543 | pmid = 9159931 | issue = 5 | date=1 May 1997 | doi=10.1093/oxfordjournals.molbev.a025790| doi-access = free }}</ref>  About 23 million years ago another group of bearlike land mammals started returning to the sea. These were the [[pinniped]]s (seals).<ref>{{
cite journal
| first1=John J. |last1=Flynn
|last2=Finarelli |first2=John
| title=Molecular Phylogeny of the Carnivora
| journal=Systematic Biology
| year=2005
| volume=54
| pages=317–337
| pmid=16012099
| issue=2
| doi=10.1080/10635150590923326
|last3=Hsu |first3=Johnny
|last4=Nedbal |first4=Michael
|display-authors=1
| doi-access=free
}}</ref> What had become walking limbs in  cetaceans and seals evolved further, independently in a reverse form of convergent evolution, back to new forms of swimming fins. The forelimbs became [[Flipper (anatomy)|flippers]] and, in pinnipeds, the hind limbs became a tail terminating in two fins (the cetacean [[Whale#Evolution|fluke]], conversely, is an entirely new organ).<ref>Felts WJL [https://books.google.com/books?id=KyxELyTDlsQC&pg=PA255 "Some functional and structural characteristics of cetacean flippers and flukes"] {{Webarchive|url=https://web.archive.org/web/20231216100000/https://books.google.com/books?hl=en&lr=&id=KyxELyTDlsQC&oi=fnd&pg=PA255#v=onepage&q&f=false |date=2023-12-16 }} Pages 255–275 ''in:'' Norris KS (ed.) ''Whales, Dolphins, and Porpoises'', University of California Press.</ref> Fish tails are usually vertical and move from side to side. Cetacean flukes are horizontal and move up and down, because cetacean spines bend the same way as in other mammals.<ref>[http://evolution.berkeley.edu/evolibrary/article/evograms_03 The evolution of whales] {{Webarchive|url=https://web.archive.org/web/20201216005644/https://evolution.berkeley.edu/evolibrary/article/evograms_03 |date=2020-12-16 }} ''University of California Museum''. Retrieved 27 November 2012.</ref><ref>{{cite journal | last1 = Thewissen | first1 = JGM | last2 = Cooper | first2 = LN | last3 = George | first3 = JC | last4 = Bajpai | first4 = S | year = 2009 | title = From Land to Water: the Origin of Whales, Dolphins, and Porpoises | url = http://www.evolbiol.ru/large_files/whales.pdf | journal = Evo Edu Outreach | volume = 2 | issue = 2 | pages = 272–288 | doi = 10.1007/s12052-009-0135-2 | s2cid = 11583496 | doi-access = free | access-date = 2012-11-26 | archive-date = 2020-07-31 | archive-url = https://web.archive.org/web/20200731153046/http://www.evolbiol.ru/large_files/whales.pdf | url-status = live }}</ref>

[[Ichthyosaur]]s are ancient reptiles that resembled dolphins. They first appeared about 245 million years ago and disappeared about 90 million years ago.
<blockquote>
"This sea-going reptile with terrestrial ancestors converged so strongly on fishes that it actually evolved a [[dorsal fin]] and tail in just the right place and with just the right hydrological design. These structures are all the more remarkable because they evolved from nothing — the ancestral terrestrial reptile had no hump on its back or blade on its tail to serve as a precursor."<ref name="Martill, 1993">Martill D.M. (1993). "Soupy Substrates: A Medium for the Exceptional Preservation of Ichthyosaurs of the Posidonia Shale (Lower Jurassic) of Germany". ''Kaupia – Darmstädter Beiträge zur Naturgeschichte'', '''2''' : 77–97.</ref></blockquote>
The biologist [[Stephen Jay Gould]] said the ichthyosaur was his favorite example of [[convergent evolution]].<ref>Gould, Stephen Jay (1993 [https://archive.org/details/eightlittlepiggi00goul "Bent Out of Shape"] in ''Eight Little Piggies: Reflections in Natural History''. Norton, 179–94. {{ISBN|9780393311396}}.</ref>
<!-- [[Wing]]s are foil type fins used to generate lift on [[flying animal]]s and aircraft, although they are sometimes referred to as fins. The vertical tail fin found on most [[fixed-wing aircraft]] is known as a [[vertical stabilizer]].

;Terminology
There is some degree of overlap and interchangeably between the term ''fin'' and other terms. Most typically, a fin refers to a thin component or appendage attached to a larger body which is submerged in water. Fin-like structure which occur in other contexts are can be referred to by other terms, such as flipper, foil, wing, flap, keel sail or blade.

The term ''wing'' refers to the large fin-like structure that produce lift, particularly in air, such as the main wings of an airplane or bird.

The term ''wing'' often refers to larger fin-like structure that produce lift, particularly in air, such as the main wings of an airplane or bird. Smaller foil-like appendages not used primarily for lift, are still referred to as''fins'', such as ''tail fins''. Birds are said to''flap'' their wings, and the small fin-like appendages to wings that are used to modify their shape are called ''flaps''.. -->