Holectypoida

The Holectypoida are an order of sea urchins related to the sand dollars. The order consists of just two living genera, but was once more diverse.

Holectypoida
Temporal range: Lower Jurassic–recent
Echinoneus cyclostomus
Scientific classification
Kingdom:
Animalia
Phylum:
Echinodermata
Class:
Echinoidea
Superorder:
Gnathostomata
Order:
Holectypoida

Duncan, 1889
Family:
Echinoneidae

Agassiz, 1847
Genera

Echinoneus
Micropetalon

Description and characteristics

In appearance, the living holectypoids are similar to sand dollars, but with less flattened bodies and an oval outline. They also lack the petal-like patterns found on the bodies of sand dollars.

Taxonomy

According to World Register of Marine Species :

  • family Anorthopygidae Wagner & Durham, 1966b †
  • family Coenholectypidae Smith & Wright, 1999 †
  • family Discoididae Lambert, 1900
  • family Holectypidae Lambert, 1900 †

References
  • Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 981. ISBN 0-03-056747-5.


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