|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||Age range and collections|
Echinoidea - Tithoniidae
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|C. G. Barras 2007||Tithoniids with ambulacral zones as wide as the interambulacral zones at the ambitus. The ambulacra are apetaloid, with microscopic pore pairs. Ambulacrum III lies in a shallow groove sub-ambitally and the peristome faces slightly towards the anterior. Plastron plating is meridosternous (cf. Solovjev 1971: fig. 30a). The apical disc is exocyclic and the periproct marginal (Solovjev 1971: fig. 30a). A small number of catenal plates may occur between the trivium and bivium.|