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Fossil range: Cambrian–Silurian
Eocrinoid holdfasts (Middle Ordovician, Utah)
Eocrinoid holdfasts (Middle Ordovician, Utah)
Colourful reconstruction of Gogia ojenai
Colourful reconstruction of Gogia ojenai
Scientific classification
Kingdom: Animalia
Phylum: Echinodermata
Subphylum: Blastozoa
Class: Eocrinoidea
Jaekel, 1899
Included groups
Excluded groups


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.


  1. ^ Prothero, D.R.,2004, Bringing Fossils to Life; An Introduction to Paleobiology (2 ed.):New York, The McGraw-Hill companies, p. 324
  2. ^ Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 1007–1008. ISBN 0-03-056747-5. 
  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).

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Preceded by Proterozoic Eon Phanerozoic Eon
Paleozoic Era Mesozoic Era Cenozoic Era
Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Paleogene Neogene 4ry