Sarcopterygii 235980 223322501 2008-07-03T15:44:18Z Grebaldar 7387784 {{Taxobox | name = Sarcopterygii | fossil_range = [[Late Silurian]] – Recent | image = Coelacanth-bgiu.png | image_width = 200px | image_caption = [[Coelacanth]], ''Latimeria chalumnae'' | regnum = [[Animal]]ia | phylum = [[Chordate|Chordata]] | subphylum = [[Vertebrate|Vertebrata]] | infraphylum = [[Gnathostomata]] | superclassis = [[Osteichthyes]] | classis = '''Sarcopterygii''' | subdivision_ranks = Subclasses | subdivision = * [[Coelacanthimorpha]] — Coelacanths * [[Dipnoi]] — Lungfishes * [[Tetrapodomorpha]] — Tetrapods and their extinct relatives. }} '''Sarcopterygii''' (from Greek ''sarx'', flesh, and ''pteryx'', fin) is traditionally the [[class (biology)|class]] of lobe-finned [[fish]]es, consisting of [[lungfish]] and [[coelacanth]]s. ==Characteristics== {{Sectstub|date=May 2008}} Sarcopterygians are bony fish with lobed paired fins, which are joined to the body by a single bone <ref>Clack, J. A. (2002) Gaining Ground. Indiana University </ref>. These fins evolved into legs of the first [[tetrapod]] land vertebrates, [[amphibian]]s. They also possess two dorsal fins with separate bases, as opposed to the single dorsal fin of actinopterygians (ray-finned fishes). The braincase of sarcoptergygians primitively has a hinge line, but this is lost in tetrapods and lungfish. Many early sarcopts have a symmetrical tail. Most taxonomists who subscribe to the [[cladistics|cladistic]] approach include the grouping Tetrapoda within this group, which in turns consists of all species of four-limbed [[vertebrate]]s.<ref name="Nelson">{{cite book|title=[[Fishes of the World]]|last=Nelson|first=Joseph S.|publisher=[[John Wiley & Sons]], Inc|year=2006|isbn=0-471-25031-7}}</ref> The fin-limbs of sarcopterygiians show such a strong similarity to the expected ancestral form of tetrapod limbs that they have been universally considered the direct ancestors of tetrapods in the scientific literature. ==Evolution of Sarcopterygii== [[Image:Fishapods.jpg|thumb|right|350px|In [[Devonian|Late Devonian]] [[vertebrate]] speciation, descendants of [[Pelagic zone|pelagic]] lobe-finned fish — like ''[[Eusthenopteron]]'' — exhibited a sequence of adaptations:<ul> <li>''[[Panderichthys]]'', suited to muddy shallows; <li>''[[Tiktaalik]]'' with limb-like fins that could take it onto land; <li>[[Tetrapod|Early tetrapods]] in weed-filled swamps, such as:<ul> <li> ''[[Acanthostega]]'', which had feet with eight digits, <li> ''[[Ichthyostega]]'' with limbs.</ul></ul> Descendants also included pelagic lobe-finned fish such as [[coelacanth]] species.]] Sarcopterygians are generally accepted to belong to the [[Osteichthyes]] group, or bony fishes, characterized by their bony skeleton instead of [[cartilage]]. However, due to the vast differences between Sarcopterygii and Osteichthyes in fin structure, respitory structure, and circulatory structure, some taxonomists are now beginning to consider Sarcopterygii a sister superclass to Osteichthyes, instead of a class below them. The oldest Sarcopterygians were found in the Uppermost [[Silurian]]. The first Sarcopterygian closely resembled [[Acanthodians]]. The Sarcopterygians closest relatives were the [[Actinopterygians]] — [[ray-finned fishes]]. Sarcopterygians probably evolved in the oceans, but they later came into [[freshwater]] habitats to avoid the predatory [[placoderms]] — which were dominant in the Early–Middle [[Devonian]] seas. As Sarcopterygians evolve in the Early Devonian, the line splits into two main lineages — the [[Coelacanth]]s, and the [[Rhipidistia]]. The Coelacanths appeared in the Early Devonian, and stayed in the oceans; the coelacanths' heyday was the Late Devonian and [[Carboniferous]], as they were more common during those periods than in any other period in the Phanerozoic. [[Coelacanths]] still live today in the [[ocean]]s. [[Rhipidistian]]s appeared about the same time as the Coelacanths, but unlike them, Rhipidistians left the ocean world and migrated into the freshwater habitats, their ancestors probably lived in the oceans near the [[river]] mouths ([[estuaries]]). The Rhipidistians in turn split into two major groups — the [[lungfishes]], and the [[tetrapodomorph]]s. The lungfishes' greatest diversity was in the [[Triassic]] Period, but today, there are fewer than a dozen genera left. The lungfishes evolved the first proto-lungs and proto-limbs. The lungfishes, ancient and modern, used their stubby fins (proto-limbs) to walk on land and find new water if their waterhole was depleted, and used their lungs to breathe air and get sufficient oxygen. The tetrapodomorphs have the same identical anatomy as the lungfishes, who were their closest kin, but the tetrapodomorphs appear to have stayed in water a little longer until the Late [[Devonian]]. [[Tetrapods]] — four legged vertebrates were the terapodomorphs' descendants. Tetrapods appeared in the Late [[Devonian]] epoch. Non-tetrapod sarcopterygians continued to towards the end of Paleozoic Era. They suffered heavy losses during the [[Permian-Triassic extinction event]]. {{Sectstub|date=May 2008}} ==Taxonomy and Phylogeny== [[Image:Latimeria chalumnae01.jpg|thumb|right|225px|Other than aquatic tetrapods, such as turtles or whales, Coelacanths are the only sarcopterygians that still live in the ocean.]] * '''Class SARCOPTERYGII''' ** '''[[Actinistia]]''' *** ''[[Eoactinistia]]''<!-- BiolLett2:443 --> *** '''Subclass [[Coelacanthimorpha]]''' **** Order [[Coelacanthiformes]] ***** Family [[Latimeriidae]] ****** ''[[Macropoma]]'' ****** ''[[Latimeria]]'' ** '''[[Rhipidistia]]''' ***'''Subclass [[Dipnoi]]''' **** Order [[Ceratodontiformes]] **** Order [[Lepidosireniformes]] ***'''Subclass [[Tetrapodomorpha]]''' **** Order [[Rhizodontida]] **** Superorder [[Osteolepidida]] ***** Family [[Tristichopteridae]] ****** ''[[Eusthenopteron]]'' ****** ''[[Hyneria]]'' ***** Order [[Osteolepis|Osteolepiformes]] **** Order [[Panderichthys|Panderichthyida]] ****''[[Tiktaalik]]'' **** '''[[Tetrapoda]]''' ==See also== * [[Actinopterygii]] — ray-finned fishes ==References== <references/> {{Chordata}} {{Sarcopterygii}} [[Category:Lobe-finned fish| ]] [[Category:Bony fish]] [[ar:لحميات الزعانف]] [[bg:Ръкоперки]] [[ca:Sarcopterigi]] [[cs:Nozdratí]] [[de:Fleischflosser]] [[et:Sagaruimsed]] [[es:Sarcopterygii]] [[eo:Sarkopterigo]] [[fr:Sarcopterygii]] [[it:Sarcopterygii]] [[he:בעלי סנפירים בשרניים]] [[la:Sarcopterygii]] [[lt:Mėsingapelekės žuvys]] [[hu:Bojtosúszójú halak és tüdőshalak]] [[nl:Kwastvinnigen]] [[ja:肉鰭綱]] [[nn:Kjøtfinnefisk]] [[oc:Sarcopterygii]] [[pl:Mięśniopłetwe]] [[pt:Sarcopterygii]] [[qu:Aycha wayt'ana]] [[ru:Лопастепёрые рыбы]] [[simple:Sarcopterygii]] [[sk:Násadcoplutvovce]] [[sr:Саркоптеригије]] [[fi:Varsieväiset]] [[sv:Lobfeniga fiskar]] [[vi:Lớp Cá vây thùy]] [[tr:Et yüzgeçliler]] [[uk:Лопастепері]] [[zea:Kwastvinnigen]] [[zh:肉鳍鱼类]]