A new cyclocystoid (Echinodermata) from the Late Ordovician of Kentucky, U.S.A.

Abstract

Cyclocystoids are one of the rarest and most enigmatic of the extinct echinoderm groups. Despite recent systematic revision (Smith and Paul, 1982), their basic anatomy and functional morphology remain poorly understood. Smith and Paul (1982) recognized eight genera and 39 species ranging in age from Lower Ordovician to Late Devonian. Since then, one new genus and species,Monocycloides oelandicus, has been established by Berg-Madsen (1987), and the range of the genusSievertsiahas been extended to the Middle Devonian of the U.S.A (Fluegeman and Orr, 1990). In addition, undescribed cyclocystoid marginal ossicles have been found in the Lower Carboniferous of Ireland (G. D. Sevastopulo, personal communication). Here we record an additional new species from the Late Ordovician of Kentucky.