Bessarabian (Tortonian, Late Miocene) fish otoliths from a transitional freshwater-brackish environment

Abstract

The Mykhailivka sedimentary section in southern Ukraine of middle (Bessarabian) to late (Khersonian) Sarmatian s.l. age is well known for its rich vertebrate finds in alternating marginal marine to estuarine and lacustrine environments. Here we describe fish otoliths obtained from sediments from a supposedly estuarine environment that had already yielded fossil fish bones and teeth described earlier. The otolith association is dominated by three species of gobiids, which are all related to the endemic extant Ponto-Caspian gobiid fauna. One species - Neogobius bettinae n. sp. - is described here. Rare associated species are Morone cf. nobilis, so far only known from the North Sea Basin, and a sciaenid. All otolith-based species represent euryhaline groups of fishes that are known today to commonly migrate from marine into brackish waters or are adapted to brackish and freshwater environments.