{{Short description|Extinct genus of proarticulatan fossil}} {{Speciesbox | fossil_range = late Ediacaran<br />~{{fossilrange|555}} | image = | image_caption = Fossil of ''M. ovata''. | genus = Marywadea | parent_authority = Glaessner, 1976 | species = ovata | authority = Glaessner & Wade, 1966 | synonyms = * ''Spriggina ovata''<br/><small>Glaessner & Wade, 1966</small> }}
'''''Marywadea''''' is an extinct proarticulate organism from the late Ediacaran of Australia. Originally described under ''Spriggina'', it is a monotypic genus, containing only ''Marywadea ovata''.
== Discovery and naming == The holotype fossil of ''Marywadea'' was found from the Ediacara Member of the Rawnsley Quartzite, in Nilpena Ediacara National Park, Flinders Ranges of South Australia in 1966, and was originally tentatively assigned under the genus ''Spriggina''.<ref name="GlaessnerWade1966">{{cite journal |last1=Glaessner |first1=Martin F. |author-link1=Martin Glaessner |last2=Wade |first2=Mary |author-link2=Mary Julia Wade |name-list-style=amp |year=1966 |title=The Late Precambrian Fossils from Ediacara, South Australia |url=http://palaeontology.palass-pubs.org/pdf/Vol%209/Pages%20599-628.pdf |url-status=usurped |journal=Palaeontology |volume=9 |issue=4 |pages=599–628 |archiveurl=https://web.archive.org/web/20130922230714/http://palaeontology.palass-pubs.org/pdf/Vol%209/Pages%20599-628.pdf |archivedate=2013-09-22}}</ref> In 1976, it would be redescribed and assigned under the new genus of ''Marywadea''.<ref name="Glaessner1976">{{cite journal |last=Glaessner |first=Martin F. |author-link=Martin Glaessner |year=1976 |title=A new genus of late Precambrian polychaete worms from South Australia |url=http://www.samuseum.sa.gov.au/Journals/TRSSA/TRSSA_v100/TRSSA_V100_p169p170.pdf |url-status=dead |journal=Transactions of the Royal Society of South Australia |volume=100 |issue=3 |pages=169–170 |archiveurl=https://web.archive.org/web/20070929094103/http://www.samuseum.sa.gov.au/Journals/TRSSA/TRSSA_v100/TRSSA_V100_p169p170.pdf |archivedate=2007-09-29}}</ref>
The generic name ''Marywadea'' is in honour of Dr. Mary Wade, who had originally noted that ''M. ovata'' may in fact be distinct from ''Spriggina'' even during the original 1966 description.<ref name="Glaessner1976"/>
== Description == ''Marywadea ovata'' is an elongate organism, getting up to {{cvt|31|mm|1}} in length, and {{cvt|15|mm|1}} at its widest. Like most proarticulates, its bears the standard glided symmetry, meaning one side is slightly offset from the other side. It has a high number of isomers, ranging between 40 and 50 all together.<ref name="GlaessnerWade1966"/> Along these isomers there are also visible tubular structures along the alternating mid-line, which have been interpreted as gonads, similar to what is seen in ''Yorgia''.<ref name="Dzik1999">{{cite journal |last1=Dzik |first1=Jerzy |last2=Ivantsov |first2=Andrey Yu. |title=An asymmetric segmented organism from the Vendian of Russia and the status of the dipleurozoa |journal=Historical Biology |date=January 1999 |volume=13 |issue=4 |pages=255–268 |doi=10.1080/08912969909386585}}</ref>
At what is considered the front, there is a notable half-moon shaped "head" region, which is usually thinner than the widest point,<ref name="Glaessner1976"/> which also contains branching features that have been compared to the digestive caecae, similar to what is seen in arthropods.<ref name="Dzik1999"/><ref>{{cite journal |last1=Peterson |first1=Kevin J |last2=Cotton |first2=James A |last3=Gehling |first3=James G |last4=Pisani |first4=Davide |title=The Ediacaran emergence of bilaterians: congruence between the genetic and the geological fossil records |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |date=27 April 2008 |volume=363 |issue=1496 |pages=1435–1443 |doi=10.1098/rstb.2007.2233|pmc=2614224 }}</ref>
== Affinities == When originally described under the genus ''Spriggina'' in 1966, ''Marywadea'' was considered to be that of a Polychaete, which was the prevailing consensus at the time for other proarticulates, like ''Dickinsonia''.<ref name="GlaessnerWade1966"/> When the original material, alongside new material, was redescribed some ten years later in 1976, ''Marywadea'' was made its own genus, but due to its similarities with ''Spriggina'', it remained under the Sprigginidae family. At this point, a more Arthropoda interpretation for both ''Spriggina'', and as such ''Marywadea'', was becoming more favoured, although many still considered a Annelida affinity for both.<ref name="Glaessner1976"/> But come 1979, a study made recounting all known annelids from the middle Cambrian at the time looked into the affinities of ''Marywadea'', and other then known proarticulates, a noted that both interpretations to be highly unlikely.<ref>{{cite journal |last1=Conway Morris |first1=Simon |title=Middle Cambrian polychaetes from the Burgess Shale of British Columbia |journal=Philosophical Transactions of the Royal Society of London. B, Biological Sciences |date=23 March 1979 |volume=285 |issue=1007 |pages=227–274 |doi=10.1098/rstb.1979.0006}}</ref>
In 2019, ''Marywadae'' was assigned to the class Cephalozoa, primarily due to its crescent shaped "head" region and small size.<ref name="Ivanstov2019">{{cite journal |last1=Ivantsov |first1=A. Yu. |last2=Fedonkin |first2=M. A. |last3=Nagovitsyn |first3=A. L. |last4=Zakrevskaya |first4=M. A. |title=Cephalonega, A New Generic Name, and the System of Vendian Proarticulata |journal=Paleontological Journal |date=September 2019 |volume=53 |issue=5 |pages=447–454 |doi=10.1134/S0031030119050046}}</ref>
==See also== *List of Ediacaran genera
==References== {{Reflist}}
{{Taxonbar|from1=Q18519092|from2=Q5158216}}
Category:Sprigginidae Category:Ediacaran life Category:Monotypic proarticulatan genera Category:Prehistoric invertebrates of Australia