The Echinoid Directory

Contributed by Andrew Smith, May 2011

Subclass Atelostomata von Zittel. 1879

Diagnosis Bilaterally symmetrical irregular echinoids with the mouth displaced anteriorly and the posterior interambulacrum differentiated on the oral surface forming a plastron.  Periproct on or close to posterior surface.
Range Early Jurassic to Recent, worldwide
Remarks The higher grouping that unites Holasteroida and Spatangoida.  Stem group members comprise the paraphyletic disasteroids.