The Echinoid Directory

 Stem group echinoids with:

• test composed of ambulacral and interambulacral plates; plating imbricate throughout
• ambulacral zones narrow, biserial with plates either uniform or with every second or third plate slightly enlarged and with a larger tubercle. Plates abut rather than overlap at perradius
• pore-pairs small and undifferentiated, positioned adradially and more or less uniserial
• interambulacra composed of four or more columns of approximately hexagonal plates
• interambulacral plates each with a single large primary tubercle; tubercles perforate and with a smooth parapet surrounding the mamelon; areole usually large and impressed
• lantern large; teeth with serrated tip
• spines moderately long to very long, usually slender (modified into short peg-like structures in one genus).

Middle Devonian to Permian, USA, Europe, former Soviet Union, Australia, India, North Africa.

The biserial ambulacra and wide zones of hexagonal interambulacral plates each bearing a large central primary tubercle that is perforate and non-crenulate distinguishes this group from other Palaeozoic echinoids. Miocidarids differs in having just two columns of plates in each interambulacral zone, and also in having a perignathic girdle of well developed apophyses. The family is almost certainly paraphyletic by exclusion of Miocidaris and all post-Palaeozoic echinoids.

The following taxa probably belong to this family but are inadequately known, being based on fragmentary material. They are treated as nomina dubia and restricted to the type material.

Palaeocidaris Desor, 1846

Eocidaris Desor, 1856

Devonocidaris Thomas, 1924