Conodont biostratigraphy of the Oandu Stage (Katian, Upper Ordovician) in NE Estonia
Conodonts from the type region of the Oandu Regional Stage (Katian, Upper Ordovician) in NE Estonia were studied.Here, here the lower boundary of the stage corresponds to a discontinuity surface at the base of the Hirmuse Formation and, in conodont succession, is marked by the disappearance of Semiacontiodus sp.and Besselodus? sp.The most character