TERRESTRIAL HABITATS IN THE LATE MIOCENE PANNONIAN BASIN SYSTEM FROM STABLE ISOTOPES IN THE HORSE HIPPOTHERIUM

Understanding the interaction between terrestrial and aquatic ecosystems is of considerable importance given modern environmental changes driven by climate, yet research efforts typically focus on one or the other. Despite a continuous sedimentary record through the Late Miocene and a lake system that has been the subject of extensive study, the Pannonian Basin System lack a well-documented geochemical record for the terrestrial environment. We use widespread and common horse Hippotherium to construct such a record and investigate ecosystem change.

Hippotherium rapidly spread through Europe in the Late Miocene, and is thought to be an opportunistic feeder rather than a dedicated grazer on the basis of skeletal morphology, co-occurring fauna, and stable isotope evidence from the earliest immigrant species. We sampled 68 Hippotherium teeth from 23 localities in the Pannonian Basin System to reconstruct feeding habitat and the composition of drinking water. Carbon isotope values indicate that these localities offered both closed and open habitats for Hippotherium through the Late Miocene. Oxygen isotope values suggest that the water sources utilized by Hippotherium ranged from standing ponds and local streams (replenished by precipitation and subject to evaporation) to extrabasinal rivers originating at high elevation. These records also offer insight into the composition of surface waters, and influences on lake hydrology within the basin.

Based on our results, the Pannonian Basin System seems to have been insulated from regional climate changes, or at the very least did not experience uniform change. Central Europe is understood to experience general cooling, drying, and opening of ecosystems through the Late Miocene, although the magnitude and timing of that climate change varies with different proxies. It is possible that the discrepancies between various proxies are the consequence of differences in geographic scale and temporal resolution.