Order Clypeasteroida Agassiz 1836 (sand dollar)
Full reference: L. Agassiz. 1836. Prodrome d'une monographie des radiaires ou échinodermes. Mémoires de la Société des Sciences Naturelles de Neuchâtel 1:168-199
Parent taxon: Neognathostomata according to A. Kroh and A. B. Smith 2010
See also Clark 1904, Hall 1962, Linder et al. 1988 and Sepkoski 2002
Sister taxa: Apatopygidae, Archiaciidae, Bothryopneustes, Cassiduloida, Clypeidae, Clypeolampadidae, Echinolampadoida, Nucleolitidae, Pygaulidae
Subtaxa: Clypeasterina Conoclypeidae Faujasiidae Laganina Oligopygidae Plesiolampadidae Prowillungaster Rotulina Runa Scutellina Tournoueraster Willungaster
Ecology: slow-moving semi-infaunal detritivore