Misszhouia

{{Short description|Extinct genus of trilobites}} {{Automatic taxobox | fossil_range = {{fossilrange|521|525|Atdabanian}} | image = Naraoia longicaudata.jpg | image_caption = ''M. longicaudata'' fossil | image2 = Misszhouia.png | image2_caption = Life restoration of ''M. longicaudata'' | taxon = Misszhouia | authority = Chen, Edgecombe & Ramsköld 1997 | subdivision_ranks = Species | subdivision = * ''M. canadensis'' Mayers, Aria & Caron, 2018<ref name=":0" /> * ''M. longicaudata'' (Zhang & Hou 1985) (type) | synonyms = *''Naraoia longicaudata'' Zhang & Hou 1985 }}

'''''Misszhouia''''' is a genus of small to average sized (up to {{convert|6|cm|in}} long)<ref name='Ramskold'>{{cite journal |first1=Lars |last1=Ramsköld |last2=Chen |first2=Jun-yuan |first3=Gregory D. |last3=Edgecombe |name-list-style=amp |last4=Zhou |first4=Gui-qing |year=1996 |title=Preservational folds simulating tergite junctions in tegopeltid and naraoiid arthropods |journal=Lethaia |volume=29 |issue=1 |pages=15–20 |issn=0024-1164 |url=http://www.nhm.ac.uk/resources-rx/files/ramskold-et-al-1996-preservational-folds-94162.pdf |doi=10.1111/j.1502-3931.1996.tb01832.x|bibcode=1996Letha..29...15R }}</ref> marine trilobite-like arthropods within the Naraoiidae family, that lived during the early Cambrian period. The species are ''M. longicaudata'', from the Maotianshan Shales, described in 1985, and ''M. canadensis'', from the Burgess Shale and described in 2018,<ref name=":0">{{Cite journal |last1=Mayers |first1=Benjamin |last2=Aria |first2=Cédric |last3=Caron |first3=Jean-Bernard |date=2019 |editor-last=Zhang |editor-first=Xi-Guang |title=Three new naraoiid species from the Burgess Shale, with a morphometric and phylogenetic reinvestigation of Naraoiidae |url=https://onlinelibrary.wiley.com/doi/10.1111/pala.12383 |journal=Palaeontology |language=en |volume=62 |issue=1 |pages=19–50 |doi=10.1111/pala.12383 |bibcode=2019Palgy..62...19M |s2cid=135331371 |issn=0031-0239|url-access=subscription }}</ref> although later species may belongs to genus ''Naraoia'' instead.<ref>{{Cite journal |last1=Bond |first1=Andrew D. |last2=Edgecombe |first2=Gregory D. |date=2021 |editor-last=Zhang |editor-first=Xi-Guang |title=Phylogenetic response of naraoiid arthropods to early–middle Cambrian environmental change |journal=Palaeontology |language=en |volume=64 |issue=1 |pages=161–177 |doi=10.1111/pala.12516 |bibcode=2021Palgy..64..161B |issn=0031-0239|doi-access=free }}</ref>

== Etymology == ''Misszhouia'' was named after "Miss Zhou" (Zhou Guiqin), to honour her for her skilled preparation of Chengjiang fossils.<ref name='Chen'>{{cite journal |last1=Chen |first1=Jun-Yuan |last2=Edgecombe |first2=Gregory D. |name-list-style=amp |last3=Ramsköld |first3=Lars |title=Morphological and ecological disparity in naraoiids (Arthropoda) from the Early Cambrian Chengjiang Fauna, China |journal=Records of the Australian Museum |volume=49 |issue=1 |pages=1–24 |year=1997 |url=http://australianmuseum.net.au/Uploads/Journals/17838/249_complete.pdf |doi=10.3853/j.0067-1975.49.1997.249 |issn=0067-1975}}</ref>

== Description == left|thumb|188x188px|Size comparison of two species of ''Misszhouia'' ''Misszhouia longicaudata'' is almost flat (dorso-ventrally). The upper (or dorsal) side of the body consists of a non-calcified headshield (cephalon) and tailshield (pygidium) without body segments between. The body is narrowed at the articulation between cephalon and pygidium. The long many-segmented antennae are directed forward. There are no eyes. The gut has a relatively small diameter, and there are four pairs of relatively small digestive sacs (or caeca) in the cephalon only, and no branches towards the edge of the cephalon (unlike ''Naraoia''). There are 25 limb pairs<ref name='Ramskold'/> with two branches on a common base, like ''Naraoia'' and trilobites. The outer branch (or exopod) has many parallel long fine flattened side branches (setae) that probably functioned as gills with a large surface area. This exopod is attached along the whole length of the base segment (coxa) and at least the proximal part of the first segment of the inner branch (endopod). The shaft of the exopod tapers gently towards its tip. The endopod is composed of seven podomeres including a terminal claw.<ref name='Chen'/>

=== Differences from ''Naraoia'' === The sister genus ''Naraoia'' differ from ''Misszhouia longicaudata'' in having the following characteristics: *A large, ramifying anterior pair of digestive branches (or diverticula) almost reaching the cephalon edges. *A bloated, mud-filled gut. *Laterally deflected antennae.<ref name='Chen'/>

== Distribution == ''Misszhouia longicaudata'' has been collected from the Lower Cambrian (late Atdabanian) of China (Yu'anshan Member of the Heilinpu Formation at Maotia’shan, the classic Chengjiang locality)<ref name='Chen'/> and also been found in the Niutitang Formation.<ref>{{cite journal |last1=Steiner |first1=Michael |last2=Zhu |first2=Maoyuan |last3=Zhao |first3=Yuanlong |name-list-style=amp |first4=Bernd-Dietrich |last4=Erdtmann |title=Lower Cambrian Burgess Shale-type fossil associations of South China |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=220 |issue=1–2 |pages=129–152 |year=2005 |url=https://paleobiodb.org/classic/displayCollResults?collection_no=86849 |doi=10.1016/j.palaeo.2003.06.001|bibcode=2005PPP...220..129S |url-access=subscription }}</ref> ''Misszhouia canadensis'' is known from the Middle Cambrian Burgess Shale in the Marble Canyon (Kootenay National Park).<ref name=":0" />

== Ecology == All Naraoids were probably marine bottom dwellers. ''Misszhouia'' probably lived as a predator or scavenger. This can be deduced from the robust and spiny basal segments of the legs, which resemble the gnathobases of trilobites. These were likely used for chewing. Such carnivorous behaviour is confirmed by the relatively small digestive system, that indicates high nutrition value food.<ref name='Chen'/>

== Taxonomy == ''Misszhouia longicaudata'' was formerly considered a member of the genus ''Naraoia'', originally known as "''Naraoia longicaudata''", until separated in 1997.<ref name='Chen'/><ref>{{cite web |url=http://www.taxonomy.nl/Taxonomicon/TaxonTree.aspx?id=647099 |title=Genus †Misszhouia - Hierarchy |website=The Taxonomicon |archive-url=https://web.archive.org/web/20160303191205/http://www.taxonomy.nl/Taxonomicon/TaxonTree.aspx?id=647099 |archive-date=3 March 2016 |url-status=dead}}</ref> A cladistic analysis conducted in 2021 suggested that ''Misszhouia'' represented a monophyletic subgroup within ''Naraoia'' as traditionally broadly defined.<ref>{{Cite journal |last1=Bond |first1=Andrew D. |last2=Edgecombe |first2=Gregory D. |date=January 2021 |editor-last=Zhang |editor-first=Xi-Guang |title=Phylogenetic response of naraoiid arthropods to early–middle Cambrian environmental change |journal=Palaeontology |language=en |volume=64 |issue=1 |pages=161–177 |doi=10.1111/pala.12516 |bibcode=2021Palgy..64..161B |issn=0031-0239|doi-access=free }}</ref>

==References== {{Reflist}}

==External links== * [http://www.fossilmuseum.net/Fossil_Sites/Chengjiang/misszhouia/misszhouia.htm ''Misszhouia longicaudata''] The Virtual Fossil Museum

Category:Nektaspida Category:Maotianshan shales fossils Category:Cambrian arthropods Category:Paleozoic life of British Columbia Category:Cambrian genus extinctions Category:Artiopod genera