Eocrinoidea

Eocrinoidea Temporal range: Cambrian–Silurian PreЄ Є O S D C P T J K Pg N
	Eocrinoid holdfasts (Middle Ordovician, Utah)
	Colourful reconstruction of Gogia ojenai
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	†Eocrinoidea; Jaekel, 1899
Groups included
	Gogiida; others?;
Cladistically included but traditionally excluded taxa
	Blastoids

The Eocrinoidea are an extinct class of echinoderms that 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 the Cambrian.

The eocrinoids were a paraphyletic group that may have been ancestral to six other classes: Rhombifera, Diploporita, Coronoidea, Blastoidea, Parablastoidea, and Paracrinoidea. The earliest genera had a short holdfast and 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 conical Bolboporites with its single brachiole.[3][4] See also List 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 on Bolboporites Pander, 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 on Bolboporites Pander, 1830 (Echinodermata; Ordovician), p. 179-180, in David, B., Guille, A., Féral, J.-P. & Roux, M. (eds.), Echinoderms through time (Balkema, Rotterdam).