Article
Article
Diadematoida
Article By:
Pawson, David L Department of Invertebrate Zoology, Smithsonian Institution, Washington, DC.
Last reviewed:January 2020
DOI:https://doi.org/10.1036/1097-8542.900335
An order of sea urchins (class Echinoidea) possessing an aulodont Aristotle's lantern (jaw apparatus) with unkeeled teeth that are U-shaped in cross section, and with the apophyses not meeting at the top of the lantern. In Diadematoida, the tubercles on the test are always perforate, and the ambulacral plates are compound (Fig. 1). The test is usually depressed, but it may be subspherical, hemispherical, or pentagonal. Gill slits are deep, and the oral region is unplated. The spines are usually long, hollow, and very brittle. This order ranges from the Lower Carboniferous to Recent. See also: Echinodermata; Echinoidea
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