Life in a Central European warm-temperate to subtropical open forest: paleoecology of the rhinocerotids from Ulm-Westtangente (Aquitanian, early Miocene, Germany)

Abstract

The locality of Ulm-Westtangente yielded the richest vertebrate fauna from the Aquitanian of Germany. Its dating to the Mammal Neogene Zone 2a, a turnover in Cenozoic climate, makes it a crucial source for the understanding of faunal, palaeoecological and palaeoenvironmental specifics of the European Aquitanian. However, if most taxa from Ulm-Westtangente have been studied, very little to nothing has been done on the large herbivores and notably on the two rhinocerotids Mesaceratherium paulhiacense and Protaceratherium minutum. Here, we used a multi-proxy approach to investigate the paleoecology of these two species. The remains of the smaller species P. minutum (442 to 667 kg) are twice as abundant as those of the larger M. paulhiacense (1687 to 2576 kg), but both display a similar age structure (∼ 10 % of juveniles, 20 % of subadults and 70 % of adults), mortality curves, and mild prevalence of hypoplasia (∼ 17 %). Results from dental mesowear, microwear, and carbon isotopes indicate different feeding preferences: both were C3 feeders but M. paulhiacense had a more abrasive diet and was probably a mixed feeder. Our study on rhinocerotids also yielded new paleoenvironmental insights, such as the mean annual temperature (15.8 °C) and precipitation (317 mm/year) suggesting rather warm and dry conditions.