The Echinoid Directory

Asterocidaris sp.

Diagnostic Features
  • Test hemispherical, flattened beneath.
  • Apical disc small, less than one-quarter test diameter; plating dicyclic, with posterior oculars closer to periproct than anterior oculars. Genital plates large, with one or two large tubercles. Periproct with smooth edges.
  • Ambulacra narrow, slightly sinuous above. Plating trigeminate aborally, quadrigeminate at ambitus; compounded in diadematid style with all elements extending to perradius. Pore-pairs uniserial above and at ambitus, expanded adorally to form phyllodes. Primary tubercles large on oral surface, sharply decreasing in size at ambitus but continuing to apex.
  • Interambulacral plates a little wider than tall, dominated by a large primary tubercle. Ring of small secondaries surrounds each tubercle forming a scrobicular circle. The top two or three plates with primary tubercle very much reduced - not much larger than scoribicular tubercles, these plates also taller than wide.
  • Primary tubercles at ambitus and adorally with small, rudimentary perforate and with feeble crenulation only on their adoral side. On the aboral surface tubercles imperforate and non-crenulate. Those of the ambulacra very much smaller than those of the interambulacra.
  • Peristome large, more or less flush, with deep, open buccal notches giving the peristome edge a crenulate appearance.
  • No sphaeridial pits and no basicoronal interambulacral plate in adult.
  • Spines and lantern not known for certain.
Middle to Upper Jurassic (Bajocian-Oxfordian), Europe.

Species Included
    Classification and/or Status

    A species of Acrocidaris