The Echinoid Directory

Megaporocidaris Kier, 1977, p. 22

Diagnostic Features
  • Test small (no larger than 9 mm), subglobular; plating non-imbricate.
  • Apical disc large and not bound to the corona; plating unknown. Outline of disc pentaradial with points at ambulacra.
  • Ambulacra narrow and almost straight; composed of simple plates throughout.
  • Pore-pairs rather large and non-conjugate. Perradial tuberculate zone very narrow (equal to pore-pair in width); with single tubercle on each plate; tubercles relatively small and non-contiguous.
  • Interambulacral zones with about 7 pentagonal plates in a column.
  • Single large primary tubercle on each interambulacral plate with very prominent imperforate, non-crenulate mamelon. Areoles circular and confluent at ambitus. Mamelons largest at ambitus.
  • Single arc of scrobicular tubercles on adradial and interradial margins; no interradial zone of granules.
  • Interambulacral plates with concave centre internally.
  • Peristome similar in size to apical disc; no buccal notches.
  • No perignathic girdle developed on interior of test.
Distribution
Late Triassic (Carnian); Italy.
Name gender feminine
Type
Megaporocidaris mariana Kier, 1977, p. 23, by original designation.
Species Included
  • Only the type species.
Classification and/or Status

?Euechinoidea stem group, Triadocidaridae.

Monotypic.

Remarks

Differs from Levicidaris in having much higher ambulacral plates with smaller tubercles and more circular pore-pairs. The mamelons in Levicidaris increase in size adapically, but are largest at the ambitus and decrease adapically in Megaporocidaris.

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

Kier, P. M. 1984. Echinoids from the Triassic (St Cassian) of Italy, their lantern supports, and a revised phylogeny of Triassic echinoids. Smithsonian Contributions to Paleobiology 56, 1-41.