Article: Unusual stricklandiid brachiopods from the Upper Llandovery beds near Presteigne, Radnorshire
Both smooth and strongly ribbed stricklandiid brachiopods occur together in early Upper Llandovery beds(Ci-C3)at Presteigne. Aenigmastricklandia contorta gen. et sp. nov. is proposed for the ribbed species, while the smooth species is assigned to Stricklandia lens aff. progressa Williams. Aenigmastricklandia appears to be an early ribbed offshoot of the main stricklandiid line; a parallel development is seen in Costistricklandia, which appeared toward the end of Upper Llandovery time (C6-C6).