A Middle Miocene vertebrate assemblage from the Czech part of the Vienna Basin : implications for the paleoenvironments of the Central Paratethys

Czujan's sandpit is an abandoned quarry in the Vienna Basin (Mikulov, Czech Republic) that has yielded an important middle Miocene vertebrate assemblage. Here we re-describe the site from the perspective of sedimentology, taphonomy, and paleoenvironments, and further review the biochronology of the fauna to clarify the age. The updated faunal list includes two testudines (one trionychid and one medium-sized testudinid), and 12 species of terrestrial mammals (three proboscideans, four perissodactyls, four artiodactyls, and one carnivoran), consistent with an early Astaracian (MN6) age. The position of the Wielician/Kosovian boundary just below the floor of Czujan's sandpit, and our new biostratigraphic data, further allow us to constrain the fossil assemblage to the latest MN6 (late Badenian, ⁓13.6 Ma) and resolves a longstanding controversy about the age of the site. The site exposes a coarsening-upward succession deposited in a braid delta environment, and comprises three facies association: from bottom to top, pelagic sediments (FA1); prodelta and delta slope sediments (FA2); and distributory channel infills of the delta front and delta plain (FA3), the latter containing all the studied terrestrial vertebrates. We propose two taphonomic explanations for the genesis of the vertebrate assemblage: (1) a time-averaged assemblage generated by riverine transport, or (2) a transported assemblage from a mass death site(s), with mass death episode(s) caused by seasonal droughts in the river catchment. Our new findings allow the more precise reconstruction of late Badenian terrestrial paleoenvironments in the northwest area of the Vienna Basin and adjacent Carpathian Foredeep Basin. This region comprised a mosaic of continental habitats dominated by woodlands but also including forest patches and more open environments