The Echinoid Directory

Neognathostomata with:

• single tube foot to all ambulacral plates
• phyllodes (adoral zones of food-harvesting tube-feet) developed adorally
• no perignathic girdle or lantern.

Lower Jurassic (Toarcian) to Recent.

Neognathostomata have traditionally been divided into a monophyletic Clypeasteroida and a paraphyletic Cassiduloida. Cladistic analysis (Smith 2001) suggests that cassiduloids are a grade taxon comprising a small number of clades leading to the Clypeasteroida. The majority of Jurassic cassiduloids belong to the common stem group of living cassiduloids plus clypeasteroids.

For a key to the modern species of Cassiduloida see Mooi (1990).

The following taxa are Neognathostomata but too poorly known to compare meaningfully:

Anochanus Grube, 1869

Echinanthopsis Munier-Chalmas, 1889

Echinanthus Leske, 1778

Heteronucleus Lambert, 1911

Pseudonucleus Lambert, 1920

Rostropygus Szorenyi, 1955

Tropholampas Clark, 1923.

Mooi, R. 1990. Living cassiduloids (Echinodermata: Echinoidea): a key and annotated list. Proceedings of the Biological Society of Washington 103: 63-85.