Chitinozoans and Acritarchs from the Ordovician–Silurian Boundary of the Prague Basin, Czech Republic

Thirty acritarch and fifteen chitinozoan taxa were determined from two sections across the Ordovician–Silurian boundary at Karlík and Hlásná Třebáň in the Prague Basin, Czech Republic. A diverse acritarch assemblage was recovered from samples near the top of the upper Ordovician Kosovo Formation, just below the basal Silurian A. ascensus Biozone, but acritarchs are generally absent or very rare in the Silurian Želkovice Formation. However, a diverse assemblage was recovered from one level in the A. acuminatus Biozone. Differences between this assemblage and that from the top of the Kosovo Formation concur with other evidence for microphytoplankton extinctions close to the Ordovician–Silurian boundary. Chitinozoans are biostratigraphically important in the early Silurian black shales of the Želkovice Formation. When combined with the graptolite biostratigraphy, they offer the prospect of a more refined biostratigraphical framework for the early Silurian of the Prague Basin.