Cenomanian terrestrial paleoenvironments from the Bohemian Cretaceous Basin in Central Europe and their implications for angiosperm paleoecology

Abstract

In this paper, we reconstruct the vegetation communities of five terrestrial paleoenvironments from the Cretaceous (Cenomanian) Peruc-Korycany Formation of the Bohemian Cretaceous Basin in Czechia. Reconstructions are based on a synthesis of numerous studies of paleobotany, palynology, paleoecology, sedimentology and geochemistry analyses. Ordered in a transect from coastal marine settings to elevated hinterland regions, paleoenvironments and plant assemblages are reconstructed as follows: (1) Saltmarsh vegetation comprising a Frenelopsis-Classopollis assemblage; (2) Coastal freshwater swamp vegetation comprising a Cunninghamites-Taxodiaceaepollenites assemblage; (3) Meandering river floodplain vegetation comprising a Myrtophyllum-Perucipollis assemblage; (4) Braided river floodplain vegetation comprising a Eucalyptolaurus-Mauldinia assemblage; and (5) Vegetation of drier upland areas comprising fern prairies with angiosperms and Bennettitales - a Zamites-Ephedripites assemblage. Our study shows that in Cenomanian times, angiosperms were diversified, particularly in alluvial plains, where lauroid and platanoid angiosperms prevailed. Comparison of these Cenomanian paleoenvironments in Czechia with other Cenomanian paleoenvironments across Europe show a widespread dominance of angiosperms in the vegetation of alluvial plains across much of the continent. This contrasts with Barremian-Albian times when angiosperms occupied only disturbed habitats, and our findings suggest that angiosperm exchanged a ruderal (disturbed) strategy for a competitive strategy during the Albian-Cenomanian transition. Conversely, conifers dominated alluvial plains in Early Cretaceous times, while they rose to dominate saltmarshes and swamps in the Bohemian Cenomanian, exchanging a competitive strategy for a stress-tolerant strategy.