Palaeophragmodictya

Palaeophragmodictya
Temporal range: Late Ediacaran, 558–555 Ma
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Scientific classification
Kingdom: Animalia
Genus: Palaeophragmodictya
Gehling & Rigby, 1996
Species
  • P. reticulata
    Gehling & Rigby, 1996
  • P. spinosa Serezhnikova, 2007

Palaeophragmodictya is a Precambrian sponge-grade organism from the Ediacaran Period. Originally interpreted as a hexactinellid sponge,[1] the organism also bears some coelomate characteristics, including bilateral symmetry.[2][3]

Contents

Morphology

The organisms take the form of a round 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.[2] Some structures in the organism have been interpreted as spicules.[1][4]

Ecology

The organisms have been interpreted as tall suspension feeders, reaching 10 cm or more up into the sea water above them.[1][5]

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.[1]

Distribution

First found in the Pound group of Australia, fossils have also been recovered from the White Sea region of Russia.[2]

Other Sponge-Grade Ediacarans

See also

List of Ediacaran genera

References

  1. ^ a b c d Gehling, J. G.; Rigby, J. K. (1996), "Long expected sponges from the Neoproterozoic Ediacara fauna of South Australia", Journal of Paleontology (JSTOR) 70 (2): 185–195, ISSN 0022-3360, http://links.jstor.org/sici?sici=0022-3360(199603)70%3A2%3C185%3ALESFTN%3E2.0.CO%3B2-A 
  2. ^ a b c Serezhnikova, E. (2007), "Palaeophragmodictya spinosa sp. Nov., a bilateral benthic organism from the Vendian of the Southeastern White Sea Region", Paleontological Journal 41 (4): 360–369, doi:10.1134/S0031030107040028, http://www.maik.ru/cgi-perl/search.pl?type=abstract 
  3. ^ Botting, J. P. (2007), ""Cambrian" demosponges in the Ordovician of Morocco: Insights into the early evolutionary history of …", Geobios 40 (6): 737–748, doi:10.1016/j.geobios.2007.02.006 
  4. ^ Ivantsov, A. Y.; Malakhovskaya, Y. E.; Serezhnikova, E. A. (2004), "Some Problematic Fossils from the Vendian of the Southeastern White Sea Region", Paleontological Journal 38 (1): 1–9, http://vend.paleo.ru/pub/Ivantsov_et_al_2004_eng.pdf 
  5. ^ Yuan, X.; Xiao, S.; Parsley, R. L.; Zhou, C.; Chen, Z.; Hu, J. (2002), "Towering sponges in an Early Cambrian Lagerstätte: Disparity between nonbilaterian and bilaterian epifaunal tierers at the Neoproterozoic-Cambrian transition", Geology 30 (4): 363–366, doi:10.1130/0091-7613(2002)030<0363:TSIAEC>2.0.CO;2, ISSN 0091-7613, http://geology.geoscienceworld.org/cgi/content/abstract/30/4/363