Editing Caudata (section)

==Evolution==
The origins and evolutionary relationships between the three main groups of amphibians ([[caecilian|apodans]], [[Salamander|urodeles]] and [[Frog|anurans]]) is a matter of debate. A 2005 molecular phylogeny, based on [[Ribosomal DNA|rDNA]] analysis, suggested that the first divergence between these three groups took place soon after they had branched from the [[Sarcopterygii|lobe-finned fish]] in the [[Devonian]] (around 360 million years ago), and before the breakup of the supercontinent [[Pangaea]]. The briefness of this period, and the speed at which radiation took place, may help to account for the relative scarcity of amphibian fossils that appear to be closely related to [[lissamphibia]]ns.<ref>{{cite journal |author1=San Mauro, Diego |author2=Vences, Miguel |author3=Alcobendas, Marina |author4=Zardoya, Rafael |author5=Meyer, Axel |year=2005 |title=Initial diversification of living amphibians predated the breakup of Pangaea |journal=The American Naturalist |volume=165 |issue=5 |pages=590–599 |doi=10.1086/429523 |pmid=15795855 |s2cid=17021360 |url=https://pure.uva.nl/ws/files/3880726/39160_170248y.pdf }}</ref> However, more recent studies have generally found more recent (Late [[Carboniferous]]<ref name=SM10>{{cite journal | last1 = San Mauro | first1 = D. | year = 2010 | title = A multilocus timescale for the origin of extant amphibians | journal = Molecular Phylogenetics and Evolution | volume = 56 | issue = 3| pages = 554–561 | doi = 10.1016/j.ympev.2010.04.019 | pmid=20399871}}</ref> to Early [[Permian]]<ref name=M&L07>{{cite journal | last1 = Marjanović | first1 = D. | last2 = Laurin | first2 = M. |name-list-style=vanc| year = 2007 | title = Fossils, molecules, divergence times, and the origin of lissamphibians | journal = Systematic Biology | volume = 56 | issue = 3| pages = 369–388 | doi = 10.1080/10635150701397635 | pmid=17520502| doi-access =  }}</ref>) age for the basalmost divergence among lissamphibians.

The earliest known fossil salamanders include ''[[Kokartus|Kokartus honorarius]]'' from the [[Middle Jurassic]] of [[Kyrgyzstan]] and three species of the apparently neotenic, aquatic ''[[Marmorerpeton]]'' from England<ref>{{cite journal | last1 = de Buffrénil | first1 = V. | last2 = Canoville | first2 = A. | last3 = Evans | first3 = S. E. | last4 = Laurin | first4 = M. |name-list-style=vanc| year = 2014 | title = Histological study of karaurids, the oldest known (stem) urodeles | journal = Historical Biology |volume=27 |issue=1 |pages=109–114 | doi = 10.1080/08912963.2013.869800| s2cid = 83557507 }}</ref> and Scotland <ref name=Jonesetal2022>{{Cite journal |last1=Jones |first1=Marc E. H. |last2=Benson |first2=Roger B. J. |last3=Skutschas |first3=Pavel |last4=Hill |first4=Lucy |last5=Panciroli |first5=Elsa |last6=Schmitt |first6=Armin D. |last7=Walsh |first7=Stig A. |last8=Evans |first8=Susan E. |date=2022-07-11 |title=Middle Jurassic fossils document an early stage in salamander evolution |journal=Proceedings of the National Academy of Sciences |volume=119 |issue=30 |pages=e2114100119 |doi=10.1073/pnas.2114100119 |pmid=35858401 |pmc=9335269 |bibcode=2022PNAS..11914100J |issn=0027-8424|doi-access=free }}</ref> of a similar date.<ref>{{cite journal | last1 = Marjanovic | first1 = D. | last2 = Laurin | first2 = M. |name-list-style=vanc| year = 2014 | title = An updated paleontological timetree of lissamphibians, with comments on the anatomy of Jurassic crown-group salamanders (Urodela) | journal = Historical Biology |volume=26 |issue=4 |pages=535–550| doi = 10.1080/08912963.2013.797972| s2cid = 84581331 }}</ref> ''[[Karaurus]]'', ''[[Kokartus]]'', and ''[[Marmorerpeton]]'' are together grouped in the extinct group [[Karauridae]] according to the structure of their skull and vertebrae.<ref name="Jonesetal2022"/> They looked superficially like robust modern salamanders but lacked a number of anatomical features that characterise all modern salamanders. ''[[Karaurus sharovi]]'' from the [[Upper Jurassic]] of Kazakhstan resembled modern [[mole salamander]]s in morphology and probably had a similar burrowing lifestyle.<ref name=Naish2013/>

In 2020, new specimens of the previously enigmatic tetrapod ''[[Triassurus]]'' from the Middle Triassic of Kyrgyzstan were described, revealing it to be the oldest known caudatan <ref>{{Cite journal|last1=Schoch|first1=Rainer R.|last2=Werneburg|first2=Ralf|last3=Voigt|first3=Sebastian|date=2020-05-26|title=A Triassic stem-salamander from Kyrgyzstan and the origin of salamanders|journal=Proceedings of the National Academy of Sciences|language=en|volume=117|issue=21|pages=11584–11588|doi=10.1073/pnas.2001424117|issn=0027-8424|pmid=32393623|pmc=7261083|bibcode=2020PNAS..11711584S |doi-access=free}}</ref> and this conclusion has been supported by subsequent analyses.<ref name="Jonesetal2022"/>

The [[Cryptobranchoidea]] and the [[Salamandroidea]], also known as Diadectosalamandroidei, are likely [[sister group]]s. Some studies suggest that both groups appeared before the end of the Jurassic, the former being exemplified by ''[[Chunerpeton|Chunerpeton tianyiensis]]'', ''[[Pangerpeton|Pangerpeton sinensis]]'', ''[[Jeholotriton|Jeholotriton paradoxus]]'', ''[[Regalerpeton|Regalerpeton weichangensis]]'', ''[[Liaoxitriton|Liaoxitriton daohugouensis]]'' and ''[[Iridotriton|Iridotriton hechti]]'', and the latter by ''[[Beiyanerpeton|Beiyanerpeton jianpingensis]]''. By the [[Upper Cretaceous]], most or all of the living salamander families had probably appeared.<ref name=Naish2013/>  However, recent phylogenetic analysis suggest that several fossil species previously thought to represent [[crown group]] salamanders may actually represent members of the [[stem group]].<ref name="Jonesetal2022"/>

[[Cryptobranchoidea]] are sometimes referred to as primitive salamanders whereas [[Salamandroidea]] / Diadectosalamandroidei are referred to as advanced salamanders. However, these lables are not necessarily helpful and imply that all members of [[Cryptobranchoidea]] are unchanged and represent the ancestral condition which is not supported by the fossil record.<ref name="Jonesetal2022"/>

All known extant and extinct (fossil) salamanders fall under the [[total group]] Caudata, whereas the common ancestor of all extant salamanders and all of its descendants (extinct and extant) represent the less inclusive [[crown group]] Urodela.<ref name="larson">{{Cite journal|author1=Larson, A. |author2=Dimmick, W. | year = 1993| title = Phylogenetic relationships of the salamander families: an analysis of the congruence among morphological and molecular characters| periodical = Herpetological Monographs| volume =7| issue = 7| pages = 77–93| doi =10.2307/1466953| jstor =1466953}}</ref><ref name=Blackburn2011>{{cite journal|author1=Blackburn, D.C. |author2=Wake, D.B. | title=Class Amphibia Gray, 1825. In: Zhang, Z.-Q. (Ed.) Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness | journal=Zootaxa| volume=3148| year=2011| pages=39–55|doi=10.11646/zootaxa.3148.1.8 | url=http://mapress.com/zootaxa/2011/f/zt03148p055.pdf}}</ref> There are about 758 extant species of salamander.<ref>{{Cite web |title=State of the World's Amphibians |url=https://www.iucn-amphibians.org/state-of-the-worlds-amphibians/ |website=IUCN SSC Amphibian Specialist Group}}</ref>