The Echinoid Directory

Laurenticidaris Vadet, 1991, p. 143

Diagnostic Features
  • Large test.
  • Apical disc relatively large; plating unknown.
  • Interambulacra with 7-8 plates in a series. Primary tubercles perforate and strongly crenulate. Areoles circular and incised; separated; with scrobicular circles contiguous adorally, but becoming more widely spaced adapically.
  • Scrobicular tubercles differentiated in size from extrascrobicular tubercles. Extrascrobicular zones present except on adoral side; their tubercles mamelonate and with fine granulation in between.
  • No sutural pits or furrows.
  • Ambulacral zones weakly sinuous. Pore zones uniserial and hardly incised; about same width as perradial tuberculate zone. Pore-pairs conjugate with pores widely separated and linked by a distinct furrow. Perradial zone with primary mamelonate tubercle on every plate.
  • Perignathic girdle not seen.
  • Peristome smaller than apical disc; ca. 35% test diameter.
  • No test with attached spines. Associated in the same bed are stout fusiform spines with coarse pustular ornament. Distinct neck at base.
Distribution
Middle Jurassic (Aalenian - Bajocian), western Europe.
Name gender feminine
Type
Rhabdocidaris major Cotteau, 1878, p. 254, by original designation.
Species Included
  • Vadet (1991) included two species when erecting this taxon:
  • L. major (Cotteau, 1878); Aalenian-Bajocian, Europe
  • L. impar (Dumortier, 1875); Aalenian, western Europe (differs in spine morphology).
Classification and/or Status

Cidaroida; Rhabdocidaridae.

Probably monophyletic.

Remarks

Vadet (1991) distinguished this taxon from Rhabdocidaris primarily because of its relatively coarse scrobicular tubercles and because its ambulacral tubercles are "not incised". These features seem very minor, and the partially dolomitised type specimens provide very poor preservation of tuberculation. However, the spine morphology is distinctly different, spines of Rhabdocidaris being often rather flattened and with spinose ornamentation, whereas those of Laurenticidaris, if correctly attributed, are irregularly pustular. The other species associated here, however, has more typical thorned spines.

Cotteau originally asigned this to the Upper Toarcian  but according to Vadet (1991) this is now considered Lower Aalenian.

Vadet, A. 1991. Revision des "Cidaris" du Lias et du Dogger Europeens. Memoires de la Societe academique du Boulonnais 10, 1-176.