The high, the sharp and the rounded : paleodiet and paleoecology of Late Miocene herbivorous mammals from Greece and Iran

The Late Miocene (11.6–5.3 million years ago) was a period of global climatic cooling and aridification. These events also had an effect on land mammals, which began to adapt to the increasingly open and grass-dominated biomes. The Eurasian Pikermian fauna is a well-known example of this evolutionary trend, including many species adapted to the new environment known as the Pikermian Biome in the Eurasian midlatitudes. The aim of this study was to deduce the paleodiets of individual Pikermian herbivore taxa, to compare results across three localities as well as with with previous results, and to assess the biome they lived in. Fossil teeth of large terrestrial mammalian herbivores from three classical Late Miocene localities of the Pikermian Biome-Pikermi, Samos (Greece), and Maragheh (Iran)-were analyzed with the mesowear method. Mesowear is the wear of mammalian herbivore molar crowns, cusps, and facets that can be seen with the naked eye, and is determined by the animal's diet (browsing and/or grazing). The mesowear scores were used in a cluster analysis where the fossil taxa were clustered with modern taxa belongin to well-known dietary categories. The results indicated the dietary categories of the fossil taxa. Among individual taxa, the Maraghean rhinoceros _Chilotherium persiae_ gave a surprising browsing signal despite its hypsodonty. _Gazella_ from Pikermi and Samos clustered with browsers to browse-dominated mixed feeders, while the sample from Maragheh indicated a more grass-dominated mixed diet. The antelope _Tragoportax_ from Pikermi and Samos yielded results that indicate the Pikermian genus used more grass in its diet than the Samian one, even though Pikermi is regarded to have been more closed of the two localities. The abundant hipparionine horses, typical for the Pikermian Fauna and previously seen as an indicator of open savanna-like biomes, showed a wide range of diets, but none of the three hipparion populations included zebra-like grazers. The wide dietary range of the Maraghean mammals in the results suggests that Maragheh had a variable paleoenvironment that included both grassy openings and closed forest. The results confirm those of previous studies, depicting a fauna consisting of browsers and mixed feeders with a notable lack of specialized grazers. This suggests that the Pikermian Biome wasn't as open as the modern East African savannas, which it has been classically compared to, but instead a varied woodland with grassy openings.