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Periaster d'Orbigny, 1853, p. 269

Diagnostic Features
  • Test ovate with distinct anterior sulcus; posterior face truncate.
  • Apical disc ethmophract with four gonopores; central.
  • Anterior ambulacrum sunken from apex; pore-pairs enlarged and closely spaced adapically, presumably bearing funnel-building tube-feet
  • Paired ambulacra petaloid aborally and sunken; posterior petals shorter than anterior petals.
  • Petals with smooth, undivided perradial zone.
  • Peristome kidney-shaped and facing forward.
  • Labrum short and projecting to cover peristome in oral view; extending to second ambulacral plate. Sternal plates symmetrical with saggital median suture. Episternal plates offset.
  • Periproct on posterior truncate face.
  • Peripetalous fasciole indented at anterior, behind the anterior petals and in the posterior interambulacrum. Lateroanal fasciole present.
Distribution
Upper Cretaceous (Cenomanian), Europe.
Name gender masculine
Type
Periaster elatus, d\'Orbigny, 1853, p. 269; [Spatangus elatus Desmoulins, 1837, p. 406], by subsequent designation of Lambert 1918, p. 8.
Species Included
  • P. elatus (Desmoulins, 1837); Cenomanian, France.
  • P. undulatus (Agassiz); Cenomanian, France.
  • Numerous other species listed by Lambert & Thiery (1924) but few likely to be congeneric.
Classification and/or Status

Spatangoida, Paleopneustina, Schizasteridae.

Presumed paraphyletic.
Remarks

Differs from Hemiasteridae in having deeply indented peripetalous fasciole and a short labral plate. Close to Linthia and differing only in having an ethmophract rather than ethmolytic apical disc. Presumably the most primitive schizasterid genus.

For a discussion of this genus see Neraudeau et al. 2003.

Neraudeau, D., Cronier, C. & Villier, L. 2003. The genus Periaster and the origins of the schizasterid echinoids: a short review. Pp. 87-90 in J.-P. Feral & B. David (eds) Echinoderm Research 2001. A. A. Balkema, Rotterdam.

Orbigny, A. d' 1854-60. Paléontologie Française. Terrains Crétacés. Tome 6. Echinodermes, Échinoides irréguliers. 596 pp, pls 801-1006. G. Masson, Paris. 1-32 (July 1854); 33-64 (Oct. 1854); 65-96 (Nov. 1854); 97-128 (Jan. 1855); 129-192 (Mar. 1855); 193-208 (May 1855); 209-224 (Aug. 1855); 225-272 (Nov. 1855); 273-320 (Oct. 1856) pp. 273-352 (Oct. 1856), pp. 353-384 (1857), pp. 385-400 (1858), pp. 401-432 (1858), pp. 433-596 (1860).