View source for Myllokunmingia

{{Short description|Extinct genus of jawless fishes}}
{{speciesbox
| image = Myllokunmingia fengjiaoa RCCBYU-10200a.png
| image_caption = Fossil of ''Myllokunmingia fengjiaoa''
| image2 = Myllokunmingia.png
| image2_caption = An artist's conception of ''Myllokunmingia fengjiaoa''
| fossil_range = {{fossil range|518}} [[Atdabanian]]<ref>{{Cite journal|last1=Yang|first1=C.|last2=Li|first2=X.-H.|last3=Zhu|first3=M.|last4=Condon|first4=D. J.|last5=Chen|first5=J.|date=2018|title=Geochronological constraint on the Cambrian Chengjiang biota, South China|journal=Journal of the Geological Society|language=en|volume=175|issue=4|pages=659–666|doi=10.1144/jgs2017-103|bibcode=2018JGSoc.175..659Y |s2cid=135091168 |issn=0016-7649|url=http://nora.nerc.ac.uk/id/eprint/521412/1/2018-JGS-Chuan%20Yang%20et%20al.pdf}}</ref>
| genus = Myllokunmingia
| parent_authority = Shu, Zhang & Han, 1999
| species = fengjiaoa
| authority = Shu, Zhang & Han, 1999
}}

'''''Myllokunmingia''''' is a genus of [[Basal (phylogenetics)|basal]] [[chordate]] from the Lower [[Cambrian]] [[Maotianshan shales]] of [[China]] 518 mya and is thought to be a [[vertebrate]],<ref name="Shu1999" /> although this is not conclusively proven.<ref name="Donoghue2005">{{Cite journal | last1 = Donoghue | first1 = P.C.J. | last2 = Purnell | first2 = M.A. | year = 2005 | title = Genome duplication, extinction and vertebrate evolution | journal = Trends in Ecology & Evolution | volume = 20 | issue = 6 | pages = 312–319 | url = http://palaeo.gly.bris.ac.uk/Publs/donoghue/Donoghue_and_Purnell_2005.pdf | doi = 10.1016/j.tree.2005.04.008 | pmid = 16701387 | access-date = 2008-11-06 | archive-url = https://web.archive.org/web/20081217052403/http://palaeo.gly.bris.ac.uk/Publs/donoghue/Donoghue_and_Purnell_2005.pdf | archive-date = 2008-12-17 | url-status = dead }}</ref> The [[type species]] '''''M. fengjiaoa''''' is 28&nbsp;mm long and 6&nbsp;mm high. It is among the oldest possible [[craniate]]s, found in the lower Cambrian [[Chengjiang]] ({{Ma|Chengjiang}}). It appears to have a [[skull]] and skeletal structures made of [[cartilage]]. There is no sign of [[mineralization (biology)|biomineralization]] of the skeletal elements. The [[holotype]] was found in the Yuanshan member of the Qiongzhusi Formation in the Eoredlichia Zone near Haikou at Ercaicun, [[Kunming|Kunming City]], [[Yunnan]], China. Some researchers have considered the other primitive chordate ''[[Haikouichthys]]'' to be synonymous with this taxon,<ref>{{cite journal | last1 = Hou | first1 = X.-G. | last2 = Aldridge | first2 = R. J. | last3 = Siveter | first3 = D. J. | last4 = Feng | first4 = X.-H. | year = 2002 | title = New evidence on the anatomy and phylogeny of the earliest vertebrates | journal = Proc Biol Sci | volume = 269 | issue = 1503| pages = 1865–1869 | doi=10.1098/rspb.2002.2104| pmid = 12350247 | pmc=1691108}}</ref> but subsequent studies led by the British paleontologist [[Simon Conway Morris]] identified both genera to be distinct, separate taxa on the basis of different gill arrangement,<ref>{{Cite journal | doi = 10.1098/rstb.2006.1846 | last1 = Conway Morris | first1 = S. | title = Darwin's dilemma: the realities of the Cambrian 'explosion' | journal = Philosophical Transactions of the Royal Society B: Biological Sciences | volume = 361 | issue = 1470 | pages = 1069–1083 | date = 29 June 2006| pmid=16754615 | pmc=1578734}}</ref> the absence of branchial rays in ''Myllokunmingia'' and the myomeres having a more acute shape in ''Haikouichthys''.<ref>{{Cite journal |last1=Conway Morris |first1=Simon |last2=Caron |first2=Jean-Bernard |date=2012 |title=''Pikaia gracilens'' Walcott, a stem-group chordate from the Middle Cambrian of British Columbia |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1469-185X.2012.00220.x |journal=Biological Reviews |language=en |volume=87 |issue=2 |pages=480–512 |doi=10.1111/j.1469-185X.2012.00220.x|pmid=22385518 |s2cid=27671780 }}</ref>

The animal has a distinct head and trunk with a forward sail-like (1.5&nbsp;mm) [[dorsal fin]] and a [[ventral fin]]fold (probably paired) further back. The maximum height of ''M. fengjiaoa'' is at 6mm. The maximum height point is located around 11mm from the anterior. The head has five or six [[gill]] pouches with [[hemibranch]]s.  In the trunk there are 25 segments ([[myomere]]s) with rearward-facing chevrons. There is a [[notochord]], a [[pharynx]] and a [[digestive tract]] that may run all the way to the rear tip of the animal. The mouth cannot be clearly identified. There may be a [[pericardial cavity]]. There are no fin radials on M. fengjiaoa. There is only one specimen, which has the tip of the tail buried in [[sediment]].<ref name=Shu1999>{{cite journal | doi = 10.1038/46965 | year = 1999 | author = Shu, D-G. | title = Lower Cambrian vertebrates from south China | journal = Nature | volume = 402 | page = 42 | last2 = Luo | first2 = H-L. | last3 = Conway Morris | first3 = S. | last4 = Zhang | first4 = X-L. | last5 = Hu | first5 = S-X. | last6 = Chen | first6 = L. | last7 = Han | first7 = J. | last8 = Zhu | first8 = M. | last9 = Li | first9 = Y. | last10 = Chen | first10 = L-Z. | issue=6757 | bibcode=1999Natur.402...42S| s2cid = 4402854 }}</ref>

==See also==
{{Portal|Paleontology}}
* ''[[Haikouichthys]]''
* ''[[Haikouella]]''

==References==
{{Reflist}}

==External links==
* http://www.sciencenews.org/sn_arc99/11_6_99/fob1.htm {{Webarchive|url=https://web.archive.org/web/20130524090604/http://www.sciencenews.org/sn_arc99/11_6_99/fob1.htm |date=2013-05-24 }}
* https://web.archive.org/web/20030511135309/http://www.gs-rc.org/repo/repoe.htm
* [http://www.nature.com/nature/journal/v402/n6757/fig_tab/402042a0_F2.html Lower Cambrian vertebrates from south China]
* [http://news.bbc.co.uk/1/hi/sci/tech/504776.stm Oldest fossil fish caught]
{{Taxonbar|from=Q133107}}

[[Category:Prehistoric jawless fish genera]]
[[Category:Maotianshan shales fossils]]
[[Category:Cambrian fish]]


{{Paleo-jawless-fish-stub}}
{{cambrian-animal-stub}}

[[la:Myllokunmingia fengjiaoa]]
[[Category:Cambrian chordates]]
[[Category:Cambrian genus extinctions]]