The Echinoid Directory

• Test thick-shelled.
• Apical disc unknown in type; dicyclic with large genital plates in Z. regularis.
• Ambulacra almost straight; pore-pairs non-conjugate. Ambulacral plating simple throughout.
• Primary tubercle to each ambulacral plate at ambitus and above but adorally every other tubercle enlarged to generate pseudocompounding.
• Interambulacral plates about as wide as tall; dominated by large primary tubercle with sunken areole and surrounded by continuous scrobicular circle.
• Primary interambulacral tubercles perforate and non-crenulate; mamelons massive, about 35-40% of areole diameter.
• Adradial suture imbricate adapically with ambulacral plate overridden by interambulacral plates; adradial suture more vertical and tesselate adorally.
• Spines unknown.
• Perignathic girdle of small ambulacral pegs.

Late Triassic (Carnian and Norian); Peru, Italy and Vancouver, Canada.

Cidaris lancedelli Zardini, 1976, p. 12, by original designation.

• Z. lancedelli (Zardini, 1976); Carnian, Italy.
• Z. guilinii Kier, 1984; Carnian, Italy.
• Z. suessii (Laube, 1865); Carnian, Italy.
• Z. stanleyi Smith, 1994; ?Norian, Peru.
• Z. regularis Smith, 1994; Norian, Peru.
• Z. pulchellus Smith, 1994; Norian, Peru.

Euechinoida; ?Pedinoida or stem group

Probably paraphyletic (no demonstrable synapomorphy).

It differs from all other Pedinoida in having simple ambulacral plating throughout. It differs from all Triadocidaridae except for Vinchuscanchaia in having perforate tubercles at the ambitus and adapically. Vinchuscanchaia differs in having proportionally smaller mamelons to its primary tubercles which are surrounded by a distinct smooth platform. Triadocidaris is similar but has imperforate tuberculation adorally. Resembles cidaroid echinoids in appearance, but lacks apophyses internally. This appears to be the oldest known euechinoid with distinct auricles.

Compared to the type species, Z. regularis has better developed peg-like auricles, more obvious ambulacral plate compounding adorally and its apical disc is demonstrably dicyclic. It is possibly a pedinoid. Whether the other members are pedinoids or stem group euechinoids requires more complete material.

Kier, P.M. 1977. Triassic echinoids. Smithsonian Contributions to Paleobiology 30, 1-88.

Smith, A. B. (1994) Triassic echinoids from Peru. Palaeontographica A 233, 177-202.