The Echinoid Directory

 Cidaroids with:

• Coronal plating more or less tesselate (adapical interambulacral - ambulacral sutures may be somewhat imbricate in basal taxa).
• Primary interambulacral tubercles crenulate and perforate, with relatively small mamelon; scrobicular tubercles poorly differentiated; extrascrobicular tuberculation heterogeneous.
• Ambulacral plating pseudocompound, with enlarged tubercles on every second or third plate, at least adorally.
• Primary spines slender and thorned; secondary spines not flattened or adpressed.

Upper Triassic (Carnian) to Lower Cretaceous (Neocomian); Europe, North Africa, probably wider.

The retention of pseudocompound ambulacra, with every second or third plate enlarged to house a larger primary tubercle, is a primitive trait held over from miocidarids and also seen in Rhabdocidaridae and Diplocidaridae. It is unlikely that this will prove to be a monophyletic grouping. The spines are long and slender and the mamelons correspondingly smaller in all but Paracidaris.

Almost certainly a paraphyletic grade by exclusion of Diplocidaridae and Histocidaridae.

Vadet, A. 1988. Revision des "Cidaris" d'Oxfordien et du Kimmeridgien Europeens. Memoires de la Societe academique du Boulonnais 4, 1-148, pls 1-25.