The Volhynian (late Middle Miocene) marine fishes and mammals as proxies for the onset of the Eastern Paratethys re-colonisation by vertebrate fauna

The late Middle Miocene of South-Eastern Europe was the time of major basinwide physical and biogeographical transformations of marine environments with mass extinction and faunal replacement. We examined new material comprising marine fishes and mammals, re-examined earlier finds, and analysed previously published data on the marine vertebrate assemblage that lived along the western and northern edges of the Eastern Paratethys. The studied materials represent marine fishes that belong to at least four families (Clupeidae, Sparidae, Bothidae, and Scombridae), including Sarmatella doljeana, Sparus brusinai, Bothus parvulus, and indeterminate scombroids; true seals (Phocinae), the earliest seal record in the area; small toothed whales of the family Kentriodontidae, including Kentriodon fuchsii, whose presence in the Volhynian is confirmed here, and two other dwarf forms; a bizarre toothed whale Pachyacanthus, the first record in the area between the Vienna Basin and Central Asia; baleen whales, including an indeterminate member of the family Cetotheriidae, and “Archaeocetus fockii”. The material found so far hints to a low taxonomic diversity and biogeographical connections to both the synchronous Sarmatian fauna of the Central Paratethys and the later Bessarabian Eastern Paratethyan fauna. The taxonomic composition of the faunal assemblage and its biogeographical connections indicate that it has Central Paratethyan origin and shows an overall west to east direction of gradual dispersal, from the Central Paratethys through the Fore-Carpathian Basin and further east. The taxonomic composition of described Volhynian fish and mammal assemblages supports the idea of faunal connection and transition between the Central and Eastern Paratethys. GOL’DIN ET AL.: THE VOLHYNIAN (LATE MIDDLE MIOCENE) 2 Pavel Gol’din. Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, 15 Bohdan Khmelnytsky st., 01030, Kyiv, Ukraine. pavelgoldin412@gmail.com Bogdan Stelian Haiduc. Alexandru Ioan Cuza University of Iaşi, Faculty of Geography and Geology, Department of Geology, Iaşi, Romania. haiduc.bogdan91@gmail.com Oleksandr Kovalchuk. Department of Paleontology, National Museum of Natural History, National Academy of Sciences of Ukraine, 15 Bohdan Khmelnytsky st., 01030, Kyiv, Ukraine and Department of Palaeozoology, Institute of Environmental Biology, University of Wroclaw, Sienkiewicza 21, 50-335 Wroclaw, Poland. biologiest@ukr.net Marcin Górka. Faculty of Geology, University of Warsaw, Al. Żwirki i Wigury 93, 02-089 Warszawa, Poland. magurka@uw.edu. pl Pavlo Otryazhyi. Karazin Kharkiv National University, 4 Svobody sq. , 61022, Kharkiv, Ukraine. paveloo108@gmail.com Mihai Brânzilă. Alexandru Ioan Cuza University of Iaşi, Faculty of Geography and Geology, Department of Geology, Iaşi, Romania. mib@uaic.ro Elena Ionela Păun. Alexandru Ioan Cuza University of Iaşi, Faculty of Geography and Geology, Department of Geology, Iaşi, Romania. elenaionelapaun@gmail.com Zoltán Barkaszi. Department of Paleontology, National Museum of Natural History, National Academy of Sciences of Ukraine, 15 Bohdan Khmelnytsky st., 01030, Kyiv, Ukraine. zlbarkasi@ukr.net Paul Ţibuleac. Alexandru Ioan Cuza University of Iaşi, Faculty of Geography and Geology, Department of Geology, Iaşi, Romania. paul.tibuleac@uaic.ro Bogdan Gabriel Răţoi. Alexandru Ioan Cuza University of Iaşi, Faculty of Geography and Geology, Department of Geology, Iaşi, Romania. Corresponding author. bog21rat@gmail.com