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Protocardiaster Smith & Wright, 2003, p. 476

Diagnostic Features
  • Test cordate with deep anterior sulcus with sharp carina. Lower surface convex with median keel towards posterior.
  • Apical disc a little anterior of centre with four gonopores.
  • Paired ambulacra subpetaloid with small or highly reduced pore-pairs. Columns of pore-pairs approximately equally developed.
  • Frontal groove present from apex to peristome.
  • Peristome oval, facing obliquely towards the anterior.
  • Plastron plating protosternous: labral plate with horn that extends to meet second sternal plate (plate 5.a.2).
  • No primary tubercles.
  • Marginal fasciole around posterior part of test.
Distribution
Cretaceous (Cenomanian - Coniacian), western Europe.
Name gender masculine
Type
Spatangus truncatus Goldfuss 1829, p. 152 , by original designation.
Species Included
  • P. truncatus (Goldfuss, 1829); Cenomanian-Turonian, western Europe.
  • P. cotteauanus (d'Orbigny, 1855); Turonian, UK and France.
Classification and/or Status

Holasteroida, Cardiasterina stem group.

Paraphyletic by exclusion of Cardiaster and the cardiasterids.
Remarks

Very close to Pseudholaster, differing only in having a marginal fasciole around the posterior of the test. It differs from Cardiaster and Infulaster in having a protosternous rather than an metasternous plastron.

Smith, A. B. & Wright, C. W. 2003. British Cretaceous echinoids. Part 7, Atelostomata, 1. Holasteroida. Palaeontographical Society Monographs, London. Pp. 440-568, pls 139-182.