The Echinoid Directory

Contributed by Andrew Smith, October 2006

Family Heterodiadematidae Smith & Wright, 1993, p. 218

Diagnosis Diadematoids with:
  • large apical disc whose plates are not firmly bound to the corona;
  • ambulacra trigeminate with uniserial columns of pore-pairs; plating diadematid, with central element largest and all three elements overgrown by primary tubercle;
  • interambulacral plates with single primary tubercle and well developed adradial and interradial zones of granulation;
  • tubercles perforate and crenulate with a small mamelon in proportion to boss;
  • peristome with sharp and deep buccal notches with a shallow, tubercle-free groove behind bordering the adradial suture;
  • lantern and spines unknown.
Range Middle Jurassic (Bathonian) to Upper Cretaceous (Maastrichtian), Europe, North Africa, Middle East.
Species Included Heterodiadema Cotteau, 1862, Trochodiadema de Loriol, 1900; Monodiadema de Loriol, 1890, Ekerekaei Ozdikmen & Udoh, 2010.
Classification and/or Status Euechinoidea, Acroechinoidea, probably Diadematoida (lantern structure unknown at present).
Remarks Smith, A. B. & Wright, C. W. 1993. British Cretaceous echinoids. Part 3, Stirodonta 2 (Hemicidaroida, Arbacioida and Phymosomatoida, part 1). Monograph of the Palaeontographical Society London (Publication 593, part of volume 147), 199-267, pls 73-92.