Cassiduloida is an
order
Order, ORDER or Orders may refer to:
* Categorization, the process in which ideas and objects are recognized, differentiated, and understood
* Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...
of
sea urchin
Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...
s. The group was extremely diverse with many families and species during the
Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...
, but today, only seven extant species remain.
A 2019 phylogenetic systematics study by Souto et al. presented a revised classification of the cassiduloids, and hypothesised that the order probably originated in the Early Cretaceous.
Description and characteristics
Cassiduloids have a rounded or slightly oval appearance, and look somewhat similar to heart urchins, although they are actually more closely related to the sand dollars. They are distinguished from other sea urchins by the presence of smaller intervening areas between the main ambulacral areas on the oral surface. They have no lantern as adults, and the petaloids are poorly developed or absent.
List of families and genera
* family
Cassidulidae
Cassidulidae is a family of echinoderms belonging to the order Cassiduloida.
Genera:
* '' Anisopetalus''
* '' Cassidulus'' Lamarck, 1801
* '' Echinobrinus'' Ébray, 1862
* ''Eurhodia'' Haime, 1853
* '' Galerolampas'' (Cotteau, 1889)
* '' Glossast ...
(L. Agassiz and Desor, 1847)
** genus
Cassidulus (Lamarck, 1801)
** genus
Paralampas (Duncan & Sladen, 1882)
** genus
Rhyncholampas
''Rhyncholampas'' is a genus of echinoderms belonging to the family Cassidulidae
Cassidulidae is a family of echinoderms belonging to the order Cassiduloida.
Genera:
* '' Anisopetalus''
* '' Cassidulus'' Lamarck, 1801
* '' Echinobrinus'' Ébr ...
(Agassiz, 1869)
* family
Eurhodiidae fam. nov.
** genus
Australanthus (Bittner, 1892)
** genus
Eurhodia
''Eurhodia'' is a genus of echinoderms belonging to the family Cassidulidae.
The species of this genus are found in Europe and Northern America.
Species:
*'' Eurhodia baumi''
*'' Eurhodia corralesi''
*'' Eurhodia elbana''
*'' Eurhodia falc ...
(d'Archiac & Haime, 1853)
** genus
Glossaster (Lambert, 1918)
** genus
Kassandrina (Souto & Martins, 2018)
* family
Faujasiidae
Faujasiidae is a family of echinoderms belonging to the order Clypeasteroida
Sand dollars (also known as a sea cookie or snapper biscuit in New Zealand, or pansy shell in South Africa) are species of flat, burrowing sea urchins belonging to t ...
(Lambert, 1905)
* family
Neolampadidae
Neolampadidae is a family of echinoderms belonging to the order Cassiduloida
Cassiduloida is an order (biology), order of sea urchins. The group was extremely diverse with many families and species during the Mesozoic, but today, only seven ex ...
(Lambert, 1918a)
* family
Pliolampadidae (Kier, 1962) †
References
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Echinoderm orders
{{echinoidea-stub