Oligocene fishes in the western Paratethys of the Rhine Valley Rift System

Abstract

In the Rhine Valley System, two fossil sites are famous for their well‐preserved and rich marine fishfaunas: Froidefontaine (Belfort Territory, France) and Frauenweiler (S of Heidelberg, Baden‐Württemberg, Germany). Concerning general stratigraphy, both deposits belong to the Rupelian stage of the Oligocene.There is a high degree of diversification of the fishfauna, e.g. within the Syngnathoidei (Gasterosteiformes), which is also recorded from corresponding localities of the Carpathians and of the Russian Pa‐leogene. Aeoliscus heinrichi (Centriscidae) is the most frequent syngnathoid species and a second one, Aeoliscus distinctus, almost certaintly also is present in Froidefontaine. Both localities are furthermore characterized by the predominance of taxa with presumably southern relationships, that probably were established via the S‐E Parathethys. Several new taxa of Frauenweiler reveal benthic/mesopelagic affinities. The Froidefontaine fauna, by contrast, is fundamentally neritic and littoral. It indicates the presence of a spawning zone but offshore connections as well. The differences in the faunal composition are probably also due to the different geographical positions: Colder seas from the north may have more strongly affected the Frauenweiler fauna than that of Froidefontaine, which was in closer contact with warmer seas from the S.‐E. Paratethys.