The shale-dominated hemipelagic succession exposed in the southwestern part of the Prague Synform preserves the most complete Ludfordian graptolite record so far encountered from peri-Gondwanan Europe. Four graptolite biozones -the Neocucullograptus inexpectatus, Nc. kozlowskii, Pseudomonoclimacis latilobus-Slovinograptus balticus and Pristiograptus fragmentalis biozones -are recognized in the middle and late Ludfordian, between the Bohemograptus tenuis Biozone and the base of the Pridoli Series. Conodont occurrences are restricted to scattered limestone beds, but enable tentative integration of the graptolite and conodont biozonal schemes. Particular attention was paid to faunal and sedimentary changes and the carbon isotope record across the middle Ludfordian Kozlowskii extinction Event. The Kozlowskii Event caused the almost simultaneous extinction of graptolites with ventrally curved rhabdosomes. The genera Bohemograptus, Polonograptus and Neocucullograptus, along with Pseudomonoclimacis dalejensis, disappeared from the fossil record. The offshore conodont fauna recorded in the section was not strongly affected and similarly the pelagic orthocerids and nektonic Ceratiocaris passed unaffected through the extinction interval. The abundant and widespread pelagic myodocopid ostracod Entomis, however, became extinct. The late Ludfordian graptolite recovery gave origin to a novel fauna of Pridoli type from taxa that emerged or just reappeared above the Kozlowskii crisis. In Všeradice and elsewhere in the Prague Synform, the recovery, manifested by the appearance of Pseudomonoclimacis latilobus and Slovinograptus balticus, closely postdates the end of the isotope excursion but pre-dates the first appearance of the conodont index 'Ozarkodina' snajdri. Here the graptolite recovery was delayed relative to the recovery of the benthic fauna. A canalized intraformational limestone conglomerate corresponds with a gap in the sedimentary record above the Kozlowskii extinction and just below the graptolite recovery. The benthic faunas from the conglomerate matrix and pebbles permit correlation with the shallower part of the basin indicating a distinct fall in sea-level. The present data demonstrate the coincidence of the graptolite crisis with benthic faunal change and eustatic fall in sea-level manifested by facies change and the carbon isotope excursion. Polonograptus chlupaci sp. nov., from the Nc. kozlowskii Biozone, is described and several other graptolite taxa are redescribed.
Conodont faunas of the Polygnathoides siluricus Zone (Ludfordian, Ludlow) from shallow-water environments of Bohemia are characterized by relatively high taxonomic diversity that reflects an interval with taxa thriving due to increased nutrient supply in rather stable environments during the pre-Lau Event time, as has been documented globally. Although the conodont faunas in strata with P. siluricus are more diversified and variable than those in the interval instantly following, the uninterrupted ranges of several taxa (of genera Wurmiella, Ozarkodina and Delotaxis) show that the change in conodont faunas in the sections is not as drastic in Bohemia as described on Gotland and that the extinction rate was rather moderate. A detailed correlation of conodont distribution in the sections indicates, however, that a large part of the Lau Event is not preserved in the shallow water environment of the former Řeporyje Volcanic Elevation. Accordingly, timing and spatial image of the conodont extinction are thus partly obscured. Only a short interval with considerably diminished conodont elements during the lower range of Ozarkodina? snajdri with random occurrences of Pedavis latialatus, corresponds to the part of the "Icriodontid Zone" on Gotland, i.e. the uppermost part of the Lau Event. This incompleteness in record confirms sedimentary starvation in the shallow environment on the former volcanic elevation in this part of the Prague Basin.•
The current conodont biozonation near the Silurian/Devonian boundary includes problematic biozones and is revised. Global applications of the zonal concepts concerning the current standard conodont zones eosteinhornensis, remscheidensis, detorta, and woschmidti are revised. New correlations are based on conodont faunas from the Požáry section (the stratotype of the Přídolí Series, Barrandian) and the Elbersreuth Orthoceratid Limestone (Frankenwald); they enable correlations with Baltic conodont faunas. The new data show that the eosteinhornensis Zone s.s. begins amid the Přídolí. The Delotaxis "detorta" plexus is not limited to the final Přídolí because it enters before the eosteinhornensis Zone. Accordingly, the use of a detorta Zone for global correlation is not recommended. The type stratum of the very particular Icriodus woschmidti is much younger than the entry of Icriodus postwoschmidti in Podolia. A succession of a woschmidti Zone and a postwoschmidti Zone in the early Lochkovian is problematic. Three new spathognathodontid species with stratigraphic potential: Zieglerodina? ivochlupaci sp. nov., Zieglerodina? klonkensis sp. nov. and Zieglerodina? zellmeri sp. nov. are described.•
Relatively rich conodont faunas from sections in the Prague Synform (Barrandian area, Czech Republic) include a number of indexes and other important guide conodonts that can be correlated with other regions, especially with Nevada and the Spanish Central Pyrenees. The collation and detailed correlation of conodont data from the Lochkovian in two parallel sections in the Požáry quarries, together with biostratigraphic control of additional data from several (incomplete) sections with changing facies development, is the basis for a new detailed regional biozonal scale for the Lochkovian in the Prague Synform. The new subdivision follows, with modification, the global threefold conodont subdivision of the Lochkovian. Data from the Prague Synform enable further detailed subdivision of the lower, middle and upper Lochkovian into small‐scale units. The conodont distribution shows a large proportional discrepancy between the late Lochkovian elsewhere; the conodont record in the latest Lochkovian in the Prague Synform area, which appears to be rather restricted and requires further discussion. Copyright © 2012 John Wiley & Sons, Ltd.
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