Plagioptychus (Hippuritida) dominated assemblage from northern Peri-Tethys margin (Bohemian Cretaceous Basin, Cenomanian–Turonian transition)

Abstract

Rudist bivalves are frequently used as an important tool for stratigraphy and palaeoecological reconstructions in Cretaceous ecosystems. In this study, we partly refine stratigraphic ranges of rudist genera and species reported from the Bohemian Cretaceous Basin (BCB). The first occurrences of Plagioptychus haueri (Teller) and consequently, the entire genus Plagioptychus might be dated to the upper Cenomanian. The research focused on two sites exposing near-shore/shallow-water deposits, located in the north-western part of BCB. This area represents palaeobiogeographical boundary between Tethyan and Boreal Realms. Here, the Tethyan rudist fauna reaches its northern limits within the Peri-Tethyan shelfs in Central Europe. Revision resulted in detection of the following rudist species: Plagioptychus haueri, Radiolites bohemicus (both already recognised), Petalodontia aculeodentata, Radiolites sanctaebarbarae and Radiolites saxoniae. Furthermore, large numbers of rudist fragments assignable to Hippuritidina suborder, corals and other macrofauna have been detected. Localities described herein are possibly of upper Cenomanian age, even though lower Turonian origin of some of the material deposited in studied localities cannot be excluded. We assign this taphocenosis with co-occurrence of rudist and coral fauna to ‘Coral-Rudist Lithosomes’ with two distinctive rudist eco-morphotypes typical of different substrate types and/or environments. Additionally, we discuss stratigraphical position of several taxa within the context of the entire Bohemian Cretaceous Basin.