Stable isotope ecology of Miocene large mammals from Sandelzhausen, southern Germany

The carbon, oxygen, and strontium isotope composition of enamel from teeth of large Miocene herbivorous mammals from Sandelzhausen (MN5, late Early/early Middle Miocene) in the North Alpine foreland basin, were analyzed to infer diet and habitat. The mean enamel δ13C value of −11.4 ± 1.0‰ (n = 53) for the nine taxa analyzed (including proboscideans, cervids, suids, chalicotheres, equids, rhinocerotids) indicates a pure C3 plant diet for all mammals. 87Sr/86Sr ratios of ~0.710 higher than those from teeth of the western Molasse Basin (0.708–0.709) seem to indicate preferential feeding of the mammals in the northeastern Molasse Basin. The sympatric herbivores have different mean δ13C and δ18O values which support diet partitioning and/or use of different habitats within a C3 plant ecosystem. Especially the three sympatric rhinoceroses Plesiaceratherium fahlbuschi, Lartetotherium sansaniense, and Prosantorhinus germanicus show clear partitioning of plants and/or habitats. The palaeomerycid Germanomeryx fahlbuschi was a canopy folivore in moderately closed environments whereas Metaschizotherium bavaricum (Chalicotheriidae) and P. germanicus (Rhinocerotidae) were browsers in more closed forest environments. The horse Anchitherium aurelianense was probably a more generalized feeder than assumed from its dental morphology. The forest hog Hyotherium soemmeringi has the highest δ13C and lowest δ18O value of all analyzed taxa, possibly related to a frugivorous diet. Most taxa were water-dependent browsers that record meteoric water δ18O values of about −5.6 ± 0.7‰ Vienna Standard Mean Ocean Water (VSMOW). Using a modern-day mean annual air temperature (MAT)–\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \delta^{18} {\text{O}}_{{{\text{H}}_{ 2} {\text{O}}}} $$\end{document} relation a MAT of 19.3 ± 1.5°C can be reconstructed for Sandelzhausen. A Gomphotherium subtapiroideum tusk serially sampled for δ18O values does not record a clear pattern of seasonality. Thus most taxa were C3 browsers in a forested and humid floodplain environment in the Molasse Basin, which experienced a warm-temperate to subtropical climate and possibly low seasonality.