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The Echinoid Directory

Macraster Roemer, 1888, p. 191

[=Douvillaster Lambert, 1917, p. 18, type species Epiaster vatonnei Coquand, 1878]

Diagnostic Features
  • Test ovate with shallow anterior sulcus; posterior face truncate. Test with rounded ambitus, flat lower surface and depressed aboral surface.
  • Apical disc ethmophract with four gonopores (possibly with genital plate 2 separating the posterior genital plates in some specimens); central.
  • Anterior ambulacrum sunken from apex to peristome; subpetaloid. Pore-pairs laterally elongate but about half the width of petal pore-pairs. Adapical pore-pairs distinctly enlarged cf. ambital pore-pairs.
  • Petals long, parallel-sided and gently sunken. Anterior petals extend to ambitus, posterior pair a little shorter; petals open distally.
  • Peristome small and ovate; angled slightly towards frontal groove but clearly visible in oral view.
  • Labral plate long and triangular with horn extending to touch plate 5.a.2; extending to fifth ambulacral plate. Sternal plates large and asymmetric with oblique suture. Episternal plates biserially arranged.
  • Periproct on posterior truncate face; small; at about mid-height.
  • Peripetalous parafasciole (broad, diffuse zone of semi-aligned granules with scattered tubercles) in zone between petals and ambitus.
  • Aboral tubercles uniform, scattered in a groundmass of fine granules.
Distribution
Cretaceous (Albian-Cenomanian), The Americas (Peru to Texas), western Europe and North Africa.
Name gender masculine
Type
Macraster texanus, Roemer, 1888, p. 191 [=Hemiaster elegans Shumard, 1853] by original designation.
Species Included Numerous species have been described, especially from the Albian and early Cenomanian of Texas and Mexico including:
Other valid species include
Classification and/or Status

Spatangoida, stem group (toxasterids).

?
Remarks

Very close to Douvillaster, differing only in having slightly less petaloid pore-pairs in the frontal groove aborally. However, the differences are so slight that it hardly merits generic separation. The two are treated as synonymous here.

Differs from Pliotoxaster in having laterally elongate (subpetaloid) pore-pairs in the adapical part of the frontal ambulacrum rather than smaller, differentiated isopores.

Roemer, F. 1888. Macraster, eine neue Spatangoiden-Gattung aus der Kriede von Texas. Neues Jahrbuch 1888(1), 191-195, pl. 6.

Schumard, B. F. 1853. Description of the species of Carboniferous and Cretaceous fossils collected; Marcy's Natural History of the Red River of Louisiana, Appendix E. (32nd Congress, 2nd session, Senate Ex Doc. 54). Pp. 199-211