The Echinoid Directory

Stem group Neognathostomata with:

• apical system compact, tetrabasal with four gonopores; no complemental plates;
• petals well developed, strongly lanceolate in shape; ambulacral pores double below petals;
• periproct inframarginal;
• peristome small, anterior; a little invaginated;
• phyllodes well developed, expanding adorally, with pore pairs forming broad marginal bands in each half-ambulacrum; no buccal pores;
• bourrelets: basicoronal plate elongate and raised compared to adjacent phyllodes, specialized perioral spines and tubercles well developed.

Middle Jurassic (Bajocian) to Cretaceous (Cenomanian).

A distinctive clade of stem group Neognathostomata with an inframarginal periproct and elongate basicoronal plate. The Faujasiidae are very similar, differing primarily in having single pores in ambulacral plates beneath the petals and a distinct inner and outer series of pores in their phyllodes. Possibly paraphyletic with respect to Faujasiidae.