Temporal range: Lower Permian–Recent
Cidaroida is an order of primitive sea urchins, the only living order of the subclass Perischoechinoidea. All other orders of this subclass, which were even more primitive than the living forms, became extinct during the Mesozoic.
Their primary spines are much more widely separated than in other sea urchins, and they have no gills. Other primitive features include relatively simple plates in the test, and the ambulacral plates continuing as a series across the membrane that surrounds the mouth.
List of families
- family Anisocidaridae Vadet, 1999 †
- super-family Cidaridea Gray, 1825
- family Diplocidaridae Gregory, 1900 †
- family Heterocidaridae Mortensen, 1934 †
- super-family Histocidaroidea Lambert, 1900
- family Miocidaridae Durham & Melville, 1957 †
- family Polycidaridae Vadet, 1988 †
- family Rhabdocidaridae Lambert, 1900 †
- family Serpianotiaridae Hagdorn, 1995 †
- family Triadocidaridae Smith, 1994c †
Balanocidaris marginata (fossil species).
- World Register of Marine Species link: Cidaroida Claus, 1880 (+species list)
- Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 980. ISBN 0-03-056747-5.
- National History Museum. "Cidaroida". Retrieved 20 Dec 2009.
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