Lower Moscovian (Duckmantian) to lower Asselian ash beds in the continental basins of the central and western Czech Republic have yielded 15 new high-precision U–Pb single crystal zircon CA-ID-TIMS ages. These are used to improve the calibration of the West European regional terrestrial stages and their correlation to the Geological Time Scale. They also allow an improved correlation between the macrofloral biozones that are used for biostratigraphy in the European Pennsylvanian coalfields, the marine biozones on which the global Geological Time Scale was partly established, and the fresh-water and terrestrial faunal biozones. Most of the floral biozones have proved to be essentially isochronous, although the ranges of some individual but stratigraphically important taxa may differ between basins.