The Echinoid Directory

Offaster Desor, 1858, p. 333

Diagnostic Features	Test ovate with flat base, tall, domal upper surface and no anterior sulcus. Apical disc subcentral with four gonopores. All ambulacra with rudimentary pore-pairs adapically. Plastron plating meridosternous with plating biserial behind the sternal plate. Peristome small and circular; facing downwards. Periproct on short truncate posterior face. Aboral tuberculation uniform and fine. Marginal fasciole present around the posterior half of the test (may be lost in the adult).
Distribution	Upper Cretaceous (Campanian to Maastrichtian), Europe to central Asia.
Name gender	masculine
Type	Ananchytes pilula Lamarck, 1816, p. 27, by subsequent designation of Quenstedt, 1874, p. 606.
Species Included	O. pilula (Lamarck, 1816); Campanian, Europe to central Asia.
Classification and/or Status	Holasteroida, Meridosternata, Holasteridae. Monotypic.
Remarks	Differs from Echinocorys in having the periproct on a vertically truncate face and in having a marginal fasciole. Differs from Cibaster only in test profile, having a taller more domed upper surface and with the periproct below mid-height in posterior view. Galeola differs in having a projecting anal rostrum with the periproct inframarginal and angled obliquely downwards. In terms of plating, all three have a similar test construction. Ernst, G. 1971. Biometrische Untersuchungen uber die Ontogenie und Phylogenie der Offaster/Galeola-Stammesreihe (Echinoidea) aus des nordwesteuropaischen Oberkreide. Neues Jahrbuch fur Geologie und Palaontologie Abhandlungen 139, 169-225. Desor, E. 1858. Synopsis des échinides fossiles, lxviii + 490 pp., 44 pls. Reinwald, Paris. 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.