Regular euechinoids with:
Middle Jurassic (Bajocian) to Recent; worldwide.
|Species Included||Includes the families Kamptosomatidae, Echinothuriidae Pelanechinidae and Phormosomatidae|
Echinothurioids have grooved teeth and a monocyclic apical disc like diadematoids but can be distinguished from that clade by having ambulacral plates continuing across the peristome membrane. Most have non-crenulate tubercles.