Scientific name Eocrinoidea Higher classification Blastozoa | Subphylum Blastozoa Rank Class | |
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Similar Echinoderm, Gogia, Edrioasteroidea, Cystoidea, Blastozoa |
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.
![Eocrinoidea Gogia spiralis Eocrinoid Fossil](https://alchetron.com/cdn/eocrinoidea-de83d73f-018f-4ec4-a947-52dc07859f4-resize-750.jpeg)
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. An unusual Ordovician form was the conical Bolboporites with its single brachiole. See also List of echinodermata orders.
![Eocrinoidea wwwucmpberkeleyeduechinodermatagogiajpg](https://alchetron.com/cdn/eocrinoidea-aa9d87b2-5c57-4739-94d4-2cd3316be12-resize-750.jpeg)
![Eocrinoidea Virtual museum Eocrinoidea Eocrinoids](https://alchetron.com/cdn/eocrinoidea-0a18cdcc-d5ee-4b6d-b347-f366bb79a6a-resize-750.jpeg)
![Eocrinoidea Virtual museum Eocrinoidea Eocrinoids](https://alchetron.com/cdn/eocrinoidea-db08cef9-1092-40a7-afeb-22cd8d19e25-resize-750.png)