Recent developments in the Upper Ordovician and lower Silurian conodont biostratigraphy in Estonia

The current state of and the latest developments in the conodont-based biostratigraphical studies of Upper Ordovician and lower Silurian strata in Estonia are discussed. An updated conodont zonation is proposed, based on successive first and/or last occurrences of taxa as interpreted from the stratigraphical record of Estonia as well as of other parts of the world. The zonation includes mainly units proposed by different authors at different times, with some revision by the author. Currently, 32 zones (with 14 subzones) and 3 informal units can be recognized in the Upper Ordovician to upper Wenlock (Homerian) of Estonia.