{{Short description|Vendian fossil}} {{Speciesbox | fossil_range = Ediacaran, around {{Fossil range|555}} | image = Andiva ivantsovi.jpg | image_caption = Fossil of ''Andiva ivantsovi'' | genus = Andiva | parent_authority = Fedonkin, 2002 | species = ivantsovi | authority = Fedonkin 2002 }}
'''''Andiva ivantsovi''''' is a Vendian fossil, identified to be a bilaterian triploblastic animal in the Ediacaran phylum Proarticulata, known from the Winter Coast, White Sea, Russia. It was first discovered in 1977, and described as a new species in a new genus by Mikhail Fedonkin in 2002.<ref name="Fedonkin2002">{{Cite journal | last1 = Fedonkin | first1 = M. A. | title = ''Andiva ivantsovi'' gen. et sp. n. and related carapace‐bearing Ediacaran fossils from the Vendian of the Winter Coast, White Sea, Russia | doi = 10.1080/11250000209356456 | journal = Italian Journal of Zoology | volume = 69 | issue = 2 | pages = 175–181 | year = 2002 | s2cid = 85352552 | doi-access = free }}</ref> It lived about 555 million years ago. Fossils of ''Andiva'' also occur in South Australia.<ref name="Fedonkin2002"/><ref name="Gehling2009">{{Cite journal | last1 = Gehling | first1 = J. G. | last2 = Droser | first2 = M. L. | doi = 10.1016/j.earscirev.2009.03.002 | title = Textured Organic Surfaces Associated with the Ediacara Biota in South Australia | journal = Earth-Science Reviews | volume = 96 | issue = 3 | pages = 196–206| year = 2009 | bibcode = 2009ESRv...96..196G }}</ref> All known fossils of ''Andiva'' are external molds.<ref name=Jerzy2003>{{cite journal | last = Dzik | first = J. | title = Anatomical Information Content in the Ediacaran Fossils and Their Possible Zoological Affinities | journal = Integrative and Comparative Biology | year = 2003 | volume = 43 | issue = 1 | pages = 114–126 | doi = 10.1093/icb/43.1.114 | pmid = 21680416 | doi-access = free }}</ref>
==Description== thumb|163px|left|Sketch reconstruction of the ''Andiva ivantsovi'' ''Andiva'' was between {{convert|6|and|10|cm|abbr=on}} long and from {{convert|4|to|5.5|cm|abbr=on}} wide, with a bilaterally symmetrical shape, larger on the anterior end and narrower at the posterior. The anterior part features a smooth "fringe" followed by a surface "covered by fine ribs and sutura",<ref name="Fedonkin2002"/> also described as a "quilt" with narrow, tightly packed chambers<ref name="Jerzy2003"/> The symmetry of these ribs is a glide symmetry, that is, in which the corresponding segments on the left and right sides do not line up, but are staggered. This is a feature shared by other forms belonging to the proposed taxon Proarticulata.
The original reconstruction by Fedonkin proposed that the ridged surface was a convex, thin carapace made of a chitin-like, non mineralized substance, protecting the animal while "creeping or gliding" over the sea bed. In the same reconstruction, the smooth zone was considered an imprint of the soft tissue beneath the dorsal carapace.<ref name="Fedonkin2002"/>
==Association== ''Andiva'' is often found together with other species from the Ediacara biota, like ''Dickinsonia'', ''Yorgia'', ''Kimberella'', ''Parvancorina'', ''Tribrachidium'' and others.<ref name="Fedonkin2002"/>
==Taxonomy and relationships== {{cladogram| caption=Proposed cladogram of the relationships between Dipleurozoa, according to Dzik (2003) |cladogram={{clade| style=font-size:85%;line-height:75%;width:300px; |label1=Dipleurozoa |1={{clade |label1= |1= ''Dickinsonia'' |label2= |2={{clade |1=''Spriggina'' |label1= |label2= |2={{clade |1=''Yorgia'', ''Praecambridium'', ''Archaeaspinus'', ''Vendia'' |label2= |2=''Chondroplon'', '''''Andiva''''' }} }} }} }} }}
Morphologically, ''Andiva'' most closely resembles ''Ovatoscutum'', ''Chondroplon'', and, more distantly, ''Dickinsonia'', as part of the proposed phylum Proarticulata.<ref name="Fedonkin2002"/> ''Archaeaspinus'' and ''Cyanorus'' have also been directly compared to it.<ref name=Ivantsov2004>{{ cite journal | last = Ivantsov | first = A. Yu. | title = New Proarticulata from the Vendian of the Arkhangel'sk Region | journal = Paleontological Journal | year = 2004 | volume = 38 | issue = 3 | pages = 247–253 | url = http://vend.paleo.ru/pub/Ivantsov_2004_eng.pdf | access-date = 2013-02-02 | archive-url = https://web.archive.org/web/20070927022709/http://vend.paleo.ru/pub/Ivantsov_2004_eng.pdf | archive-date = 2007-09-27 | url-status = dead }}</ref>
Jerzy Dzik includes ''Andiva'' in the Dipleurozoa, with ''Chondroplon'' as the closest relative, separated from ''Dickinsonia'' and closer to ''Yorgia'', ''Praecambridium'', ''Archaeaspinus'', and ''Vendia'', since all of them share a dextrally bent dorsal medial chamber.<ref name="Jerzy2003"/>
==See also== * List of Ediacaran genera
==References== {{Reflist}}
{{Taxonbar|from=Q4754504}}
Category:Cephalozoa Category:Monotypic proarticulatan genera Category:Fossil taxa described in 2002 Category:White Sea fossils Category:Ediacaran life Category:Fossils of Russia