Benchmark data of a changing sea — Palaeogeography, Palaeobiogeography and events in the Central Paratethys during the Miocene

Abstract

The reconstruction and interpretation of terrestrial ecosystems and vegetational patterns in the Central European Miocene have to take into account the influence of a vast landlocked water body, namely the Paratethys Sea. As a northern appendage of the early Mediterranean Sea, it spanned a north–south gradient of at least 4° latitude and has been suggested to represent some kind of “palaeothermometer”, which reflected slight expansions or restrictions of climatic belts. Due to its vulnerable marine connections it was also highly susceptible to major (global) sea-level fluctuations which are reflected in phases of endemism. Hence, a fairly continuous record of marine nearshore assemblages throughout the Miocene reflects an extraordinary interplay of sea-level fluctuations, changes in climate, immigrations, and blooms in autochthonous elements. Whilst biostratigraphic implications of these patterns were recognised early in palaeontology, a biogeographic model is still lacking. The intermingling of palaeogeographic terms with those restricted to biogeography is still commonly used — a situation which can be overcome by integrating data from different biota into a new palaeobiogeographic scheme.Herein, a data-set of 1809 species-level taxa (Gastropoda and Foraminifera) serves as the base for interpretations. Gastropods in particular turned out to be of greatest value for the differentiation of palaeobiogeographic units due to sensitive reactions to all environmental parameters and occupying a wide range of ecological niches. Based on the excellent gastropod record the Proto-Danubian Province, Early Danubian P., Danubian P., Balatonian P. and a Proto-Caspian Subprovince are defined. The biogeographic reorganisations are associated with five major biotic events within the gastropod faunas. These “big five” comprise four extinctions – the late Ottnangian extinction event (LOEE), the mid-Badenian-extinction-event (MBEE), the Badenian–Sarmatian-extinction event (BSEE), the Sarmatian–Pannonian-extinction event (SPEE) – and one exceptional immigration/origination event termed the early Badenian Build-up event (EBBE).Foraminifera are less valuable for palaeobiogeographic purposes in the area and time-slice studied. Endemisms are generally lower and turn-over rates less dramatic. They are, however, very useful for stratigraphic correlations with the Mediterranean and Atlantic areas. This fairly well calibrated marine biostratigraphy of the Central Paratethys serves as stratigraphic backbone and control for continental stratigraphy.