The Echinoid Directory

 Phymosomatoids with:

• ambulacra trigeminate to polygeminate, with diadematid style compounding; all elements extending from adradial to perradial suture;
• primary tubercles perforate and crenulate.

Lower Jurassic to Lower Cretaceous, Europe, North Africa, Middle East, India, North America.

Emiratiidae and Phymosomatidae have an identical apical disc structure and a rather similar tuberculation style, with one or two large primary tubercles to each plate, ambulacral tubercles being similar in size to interambulacral tubercles at the ambitus. Emiratiidae differ from Phymosomatidae in having perforate tubercles and diadematid-style plate compounding (with all elements reaching the perradius). Both of these character states are primitive with respect to Phymosomatidae, and so this grouping is probably paraphyletic.

The following taxon probably belongs here but remains very poorly known:

Orthodiadema Lambert & Thiery, 1908

Ali, M. S. M. 1990. Cenomanian echinoids from Ras al Khaimah, United Arab Emirates. Neues Jahrbuch fur Mineralogie, Geologie und Palaontologie, Abhandlungen, 179, 97-116.