Crinoids from the Upper Ashgill (Upper Ordovician) of Wales

Abstract

A collection of small crinoids and crinoid debris from the Ashgill (Rawtheyan?) of Cnwce, near St. Clears, Dyfed, southwest Wales includes numerous crowns of Aithriocrinus strahani n. gen. and sp. incertae familiae, an indeterminate 10–armed camerate(?) and an indeterminate multiple-armed camerate. Aithriocrinus strahani was previously considered to be a cincinnaticrinid, but it is undoubtedly dicyclic and therefore a cladid. This is the only diverse fauna of complete crinoids known from the Welsh Ashgill.The monobathrid camerate Xenocrinus S. A. Miller is easily recognized from its disarticulated columnals, which are square in outline. Xenocrinus columnals are now recognized from three Hirnantian localities in Wales. Xenocrinus became extinct during the Hirnantian and not at the Rawtheyan–Hirnantian boundary, as has been suggested on the basis of crown material.