Abstract

Only two nominal species of crinoid, the diplobathrid camerates Diabolocrinus craigheadensis Ramsbottom and Diabolocrinus globularis (Nicholson & Etheridge), have been described from the Ordovician (Chatfieldian; Sandbian) Craighead Limestone Formation, Craighead quarry, near Girvan, Ayrshire. In contrast, columnal morphotaxa are represented by over 20 taxa including those in open nomenclature. Two thecae from Craighead quarry and referred to Diabolocrinus sp. or spp. preserve features of the stem facet that are similar to specimens referred to Oanducystis (col.) spp. from the same locality. These columnal morphotaxa are synonymised with Diabolocrinus and left in open nomenclature. However, Diabolocrinus is limited to Laurentia, whereas the remaining morphospecies of Oanducystis (col.) Stukalina are limited to Kazakhstan and Estonia.

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