The Echinoid Directory

Family Tiarechinidae Gregory, 1897, p. 1003


 Crown group echinoids with:

  • Test small, upper surface made entirely of apical disc plates; test plating sutured;
  • Ambulacral plating simple, pore-pairs uniserial throughout; ambulacra expanded adorally;
  • Interambulacral zones composed of just 4 plates, a basicoronal plate followed by a row of three vertically elongate plates;
  • Primary tubercle to each plate; imperforate and non-crenulate;
  • Feeble perignathic girdle on basicoronal interambulacral plate.
Middle Triassic (Carnian), Europe.

This very distinctive monospecific taxon was described in superb detail by Loven (1883), and the type refigured by Kier (1977). The large size of the apical disc and basicoronal plate suggests that this might still be a juvenile, although gonopores are open. It is impossible to confuse with any other echinoid because of its small number of interambulacral plates and their distinctive arrangement.

Loven, S. 1883. On Pourtalesia, a genus of Echinoidea. Kongliel Svenska Vetenskaps-Akademiens Handlingar new series 19, 1-95, pls 1-21.

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