The fish fauna of the Dynów Marl Member (Menilite Formation, Poland): paleoenvironment and paleobiogeography of the early Oligocene Paratethys

The Dynów Marl Member of the Menilite Formation in Poland is one of the most significant lithostratigraphic units containing fauna of the early Oligocene Paratethys. The fish fauna from this member is presented, including three shark taxa and eight teleost taxa. The connection between the Upper Rhine Graben and the Central Paratethys in the calcareous nannoplankton zone NP23 (about 30–32 Ma ago) is consistent with the occurrence of the teleost Anenchelum glarisianum and the shark Keasius parvus. The presence of the teleosts Scopeloides glarisianus, Vinciguerria obscura and Oligophus moravicus confirms the connections between the Eastern and Central Paratethys. The distribution of the ichthyofauna supports the existence of a marine connection between the North Sea, the Upper Rhine Graben, the northwestern Tethys, and the Central and Eastern Paratethys during the early Oligocene. The fish assemblage shows a high percentage of fishes, whose extant relatives are living in the depth interval between 0 and 500 m. The presence of Gonostomatidae, Phosichthyidae and Myctophidae indicates normal salinity in the deep pelagic life zones. The fish fauna show distinctly Paratethyan affinities.