Chitinozoans and acritarchs in latest Tremadoc–Early Arenig sediments of the Prague Basin, Czech Republic

Samples from the lowermost part of the Klabava Formation in the Prague Basin, Czech Republic, have yielded two assemblages of acritarchs and chitinozoans. The lower assemblage contains the acritarchs Stelliferidium cf. trifidum (Rasul) Fensome et al., Cymatiogalea messaoual Jardiné et al., Rhopaliophora palmata (Combaz and Peniguel) Playford and Martin and other taxa, in association with a monospecific assemblage of the index chitinozoan Amphorachitina conifundus Poumot.These three named and stratigraphically restricted acritarch taxa are missing from the upper assemblage, in which A. conifundus is associated with the chitinozoan species Conochitina symmetrica Taugourdeau and de Jekhowsky. The upper acritarch assemblage is characterized by Cymatiogalea spp. and Veryhachium cf. trapezconarion Loeblich. The lower acritarch assemblage is comparable with the trifidum flora, a distinctive assemblage recorded from the Anglo-Welsh area and Spain.In the Klabava Formation, A. conifundus dates the trifidum flora as latest Tremadoc or earliest Arenig. The upper acritarch assemblage is from the C. symmetrica chitinozoa Biozone, which is correlated with the Terragraptus approximatus graptolite Biozone. These results help to constrain the trifidum flora stratigraphically and indicate the composition of earliest Arenig ‘Gondwanan’ acritarch assemblages.