The Echinoid Directory

 Phymosomatoida with:

• large pentagonal apical disc; plates not bound to the corona, presumed monocyclic;
• ambulacra trigeminate to polygeminate, with all elements extending from adradial to perradial suture; plate compounding diadematid in style (central element largest);
• primary tubercles in ambulacral and interambulacral zones of comparible size; imperforate and non-crenulate.

Upper Cretaceous, Europe, North Africa, Middle East, South America.

Very like Emiratiidae in appearance but with imperforate, non-crenulate tubercles. Members of the Phymosomatidae have a similar large apical disc and imperforate tubercles, but their ambulacral plating is always phymosomatid, not diadematid and their tubercles are distinctly crenulate.

The following taxon probably belongs here but remains poorly known: Pliocyphosoma Pomel, 1883