PRIDOLI SERIES

Pridoli also spelled Prdol, also called Pridolian, the uppermost of four main divisions of the Silurian System, representing rocks deposited worldwide during the Pridoli Epoch (414 to 408 million years ago). The series' name is derived from the Prdol area of the Daleje Valley on the outskirts of Prague in the Czech Republic, where about 20-50 m (65-165 feet) of platy limestone strata rich in cephalopods and bivalves are well developed. By international agreement, the base of the Pridoli Series is defined by the first occurrence of the graptolite species Monograptus parultimus in rock exposures at the entrance to the Pozary Quarries, which lie about 1.5 km (one mile) east of Reporyje, outside of southwestern Prague. The M. parultimus biozone, in short, constitutes the global stratatype section and point (GSSP) for the base of the series. Two species of chitinozoans (a type of marine plankton), Urnochitina urna and Fungochitina kosovensis, first occur at or just above the series' base. The earliest-known simple vascular (i.e., land-dwelling) plants, of the genus Cooksonia, typically occur in the lower portions of the Pridoli Series in many parts of the world. The Pridoli Series is overlain by the Lochkovian Stage, the first stage of the Devonian System. The Pridoli Series has not been subdivided into standard stages.