Graptolite biostratigraphy and biodiversity dynamics in the Silurian System of the Prague Synform (Barrandian area, Czech Republic)

The planktic graptolites are the fossils of primary choice in biostratigraphical subdivision and correlation of off shore Silurian strata worldwide. The rapid evolution, morph ological diversity and complexity of graptolite rhab dosomes, combined with high numerical abundance and wide geographical distribution, have made graptolites the optimal biozone fossils in largely siliciclastic outer shelf and deeper marine facies. It has been a long journey from the pioneer stratigraphical studies using graptolites (Lapworth 1878, Trnquist 1879, Marr 1880, Tullberg 1883) to the globally applicable graptolite biozonal schemes and correlation charts of Particularly high resolution graptolite biozonal schemes have been attained in the oxygende p l eted offshore facies of graptolitic black shales. Inte g rated graptolite, conodont, chitinozoan, spore, and microvertebrate biostratigraphy, combined with radio metric data and carbon isotope stratigraphy, have achieved remarkably high temporal resolution for the Silurian timescale The Silurian succession is almost complete in this region and for the most part can be studied in graptolite rich, offshore marine facies. The first comprehensive biostratigraphical subdivision of the Silurian succession of the Prague Synform, proposed in this study, is based upon data from 88 graptolitebearing localities and sections, commonly studied bed by bed. New data are complemented by earlier graptolite records published by B. Bouek, A. Pibyl, H. Jaeger and J. K from other localities, in particular temporary building excavations and dump-filled abandoned quarries and brick-pits.