Palaeophragmodictya

{{Short description|Extinct genus of sponges}} {{Automatic taxobox | fossil_range = Late Ediacaran, {{Fossil range|558|555}} | image = Palaeophragmodictya spinosa パレオフラグモディクチャ.jpg | image_caption = Fossil of ''P. spinosa'' | taxon = Palaeophragmodictya | authority = Gehling & Rigby, 1996 | subdivision = * ''P. reticulata'' Gehling & Rigby, 1996 * ''P. spinosa'' Serezhnikova, 2007 }}

'''''Palaeophragmodictya''''' is an extinct genus of sponge-grade organisms from the Ediacaran Period. Originally interpreted as a hexactinellid sponge,<ref name=Gehling1996>{{citation |author1=Gehling, J. G. |author2=Rigby, J. K. | year = 1996 | journal = Journal of Paleontology | volume = 70 | issue = 2 | pages = 185–195 | title = Long expected sponges from the Neoproterozoic Ediacara fauna of South Australia |doi=10.1017/S0022336000023283 | jstor = 1306383 |bibcode=1996JPal...70..185G | issn = 0022-3360 }} </ref> the organism also bears some coelomate characteristics, including bilateral symmetry.<ref name=Serezhnikova2007>{{citation | author = Serezhnikova, E. | year = 2007 | title = ''Palaeophragmodictya spinosa'' sp. Nov., a bilateral benthic organism from the Vendian of the Southeastern White Sea Region | journal = Paleontological Journal | volume = 41 | issue = 4 | pages = 360–369 | doi = 10.1134/S0031030107040028 | bibcode = 2007PalJ...41..360S | url = http://www.maik.ru/cgi-perl/search.pl?type=abstract | access-date = 2008-08-16 | archive-url = https://web.archive.org/web/20160222164742/http://www.maik.ru/cgi-perl/search.pl?type=abstract | archive-date = 2016-02-22 | url-status = dead | url-access = subscription }}</ref><ref name=Botting2007>{{Citation | author = Botting, J. P. | year = 2007 | volume = 40 | title="Cambrian" demosponges in the Ordovician of Morocco: Insights into the early evolutionary history of … | journal = Geobios | issue = 6 | pages = 737–748 | doi = 10.1016/j.geobios.2007.02.006 | bibcode = 2007Geobi..40..737B }}</ref>

==Morphology== The organisms take the form of a rounded, dome-like bag, 7–68 mm in diameter, with an uneven margin. Radial grooves define sac-like compartments within the bag. The radial pattern has an element of bilateral symmetry. A stalk emerges from the central point of some specimens, at the top of the organism; in life, it probably extended into the water column. Ray-like filaments radiate outwards from the edge of the bag.<ref name=Serezhnikova2007/> Some structures in the organism have been interpreted as spicules.<ref name=Gehling1996/><ref name=Ivantsov2004>{{citation |author1 = Ivantsov, A. Y. |author2 = Malakhovskaya, Y. E. |author3 = Serezhnikova, E. A. |year = 2004 |journal = Paleontological Journal |volume = 38 |issue = 1 |pages = 1–9 |title = Some Problematic Fossils from the Vendian of the Southeastern White Sea Region |url = http://vend.paleo.ru/pub/Ivantsov_et_al_2004_eng.pdf |url-status = dead |archiveurl = https://web.archive.org/web/20130720183943/http://www.vend.paleo.ru/pub/Ivantsov_et_al_2004_eng.pdf |archivedate = 2013-07-20 }}</ref>

==Ecology== The organisms have been interpreted as tall suspension feeders, reaching 10 cm or more up into the sea water above them.<ref name=Gehling1996/><ref name=Yuan2002>{{citation |author1=Yuan, X. |author2=Xiao, S. |author3=Parsley, R. L. |author4=Zhou, C. |author5=Chen, Z. |author6=Hu, J. | year = 2002 | title = Towering sponges in an Early Cambrian Lagerstätte: Disparity between nonbilaterian and bilaterian epifaunal tierers at the Neoproterozoic-Cambrian transition | journal = Geology | volume = 30 | issue = 4 | pages = 363–366 | doi = 10.1130/0091-7613(2002)030<0363:TSIAEC>2.0.CO;2 |bibcode=2002Geo....30..363Y | url = http://geology.geoscienceworld.org/cgi/content/abstract/30/4/363 | issn = 0091-7613 | url-access = subscription}}</ref>

==Original description==

The genus was originally considered to be a member of the Dictyospongiidae family (Hexactinellia), and was among the first Precambrian sponges to be described.<ref name=Gehling1996/>

==Distribution==

First found in the Pound group of Australia, fossils have also been recovered from the White Sea region of Russia.<ref name=Serezhnikova2007/>

==Other sponge-like Ediacaran animals==

*''Fedomia'' *''Vaveliksia'' *''Helicolocellus'' *''Arimasia''

==See also== {{Portal|Paleontology}} *List of Ediacaran genera

==References== {{Reflist}}

Category:Precambrian sponges Category:White Sea fossils Category:Prehistoric sponge genera Category:Fossils of Russia Category:Fossil taxa described in 1996