Eocrinoidea

Eocrinoidea Temporal range:Cambrian–Silurian PreꞒ Ꞓ O S D C P T J K Pg N
	Eocrinoid holdfasts (Middle Ordovician, Utah)
	Colourful reconstruction ofGogia ojenai
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Echinodermata
Subphylum:	†Blastozoa
Class:	†Eocrinoidea; Jaekel,1899
Groups included
	Gogiida; Rhombifera; others?;
Cladisticallyincluded but traditionally excluded taxa
	Blastoids

TheEocrinoideaare an extinct class ofechinodermsthat lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, arm-bearing echinoderms, and were the most common echinoderms during theCambrian.

Eocrinoids were aparaphyleticgroup that may have been ancestral to six other classes:Rhombifera,Diploporita,Coronoidea,Blastoidea,Parablastoidea,andParacrinoidea.They may also be the progenitors of thecystoids,who are believed to be ancestral to moderncrinoids.The earliest genera had a shortholdfastand irregularly structured plates. Later forms had a fully developed stalk with regular rows of plates. They were benthic suspension feeders, with five ambulacra on the upper surface, surrounding the mouth and extending into a number of narrow arms.^[1]^[2]An unusual Ordovician form was the conicalBolboporiteswith its single brachiole.^[3]^[4]See alsoList of echinodermata orders.

References

^Prothero, D.R.,2004, Bringing Fossils to Life; An Introduction to Paleobiology (2 ed.):New York, The McGraw-Hill companies, p. 324
^Barnes, Robert D. (1982).Invertebrate Zoology.Philadelphia, PA: Holt-Saunders International. pp. 1007–1008.ISBN 978-0-03-056747-6.
^Rozhnov, S.V. 2009. Eocrinoids and paracrinoids of the Baltic Ordovician basin: a biogeographical report. IGCP Meeting, Ordovician palaeogeography and palaeoclimate, Copenhagen, p. 16.
^Rozhnov, S.V. and Kushlina, V.B. 1994. Interpretation of new data onBolboporitesPander, 1830 (Echinodermata; Ordovician), p. 179-180, in David, B., Guille, A., Féral, J.-P. & Roux, M. (eds.), Echinoderms through time (Balkema, Rotterdam).

External links

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[1] Prothero, D.R.,2004, Bringing Fossils to Life; An Introduction to Paleobiology (2 ed.):New York, The McGraw-Hill companies, p. 324

[IZ-2] Barnes, Robert D. (1982).Invertebrate Zoology.Philadelphia, PA: Holt-Saunders International. pp. 1007–1008.ISBN 978-0-03-056747-6.

[3] Rozhnov, S.V. 2009. Eocrinoids and paracrinoids of the Baltic Ordovician basin: a biogeographical report. IGCP Meeting, Ordovician palaeogeography and palaeoclimate, Copenhagen, p. 16.

[4] Rozhnov, S.V. and Kushlina, V.B. 1994. Interpretation of new data onBolboporitesPander, 1830 (Echinodermata; Ordovician), p. 179-180, in David, B., Guille, A., Féral, J.-P. & Roux, M. (eds.), Echinoderms through time (Balkema, Rotterdam).

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