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The Echinoid Directory

Contributed by Andreas Kroh, March 2016

Absurdaster Kroh, Lukeneder & Gallemi, 2014, p. 237.

Diagnostic Features
  • Test heat-shaped in outline; shallow anterior sulcus.
  • Apical disc highly modified, disjunct in which only genital plate 2 is retained and forms a bilaterally symmetrical madreporite located along midline of test. Multiple genital pores located on the most adapical interambulacral plates may be present.
  • Ambulacrum III sunken at the ambitus and differentiated from the paired ambulacra.
  • Posterior oculars and associated ambulacra separated from periproct by at least one pair of interambulacral plates.
  • Ambulacra all similar; subpetaloid or apetaloid; in the former case pore-pairs are small and circumflexed, otherwise they are minute unipores.
  • Phyllodes poorly developed, no plate crowding, few enlarged pores close to peristome.
  • Peristome strongly anterior of centre, small, subcircular; facing downwards.
  • Plastron plating protosternous or meridosternous.
  • Peripoct large, circular and positioned on vertically truncated posterior face of the test, strongly invaginated in some species.
  • Tuberculation fine scattered tubercles set in groundmass of granules.
Distribution Lower Cretaceous, Europe.
Type Absurdaster puezensis Kroh, Lukeneder & Gallemi, 2014, p. 242. Holotype: Naturmuseum Sudtirol STMN PZO 341 (CP172)
Species Included
  • A. hungaricus Kroh, Lukeneder & Gallemi, 2014; Hauterivian, Hungary.
  • A. puezensis Kroh, Lukeneder & Gallemi, 2014; Hauterivian-Barremian, Italy.
  • A. meriani (Ooster, 1865); Early Cretaceous; Switzerland.
Classification and/or Status Irregularia; Stem group Atelostomata; Collyritidae.
Remarks One of the few 'disasteroids' with a frontal notch; differs from all of them by the structure of the apical disc, which is twice disjunct (between Oc I/V and OcII/IV, as well as between OcIII and OcII/IV).

Kroh, A. Lukeneder, A. & Gallemi, J. (2014). Absurdaster, a new genus of basal atelostomate from the Early Cretaceous of Europe and its phylogenetic position. Cretaceous Research 48: 235-249.