Feeding strategies of circum‑Mediterranean hipparionins during the late Miocene: Exploring dietary preferences related to size through dental microwear analysis

International audienceThe adaptive radiation of hipparionins after their Old World dispersal was linkedwith a trend towards smaller body sizes. The appearance of the small-sized forms hasusually been associated to open environments and grazing diets. A recent approach,moreover, highlights the role of life history modifications related to habitat conditions astriggers of their size shifts. Here, we test the relationship between hipparionin size anddiet analyzing the dental microwear textures of different-sized hipparionins fromVallesian and Turolian circum-Mediterranean localities. Our results show that hippari-onins were mainly mixed-feeders and that there was no general link between body sizeand diet. However, we identified broader feeding spectra in western Mediterraneansmaller forms and more specialized grazing diets in larger ones, a differentiation notfound in the eastern Mediterranean hipparionins. At odds with the notion of more openhabitats eastward, we detected a larger browsing component in eastern hipparionindiets. The consumption by extant equids of more woody browse during the dry seasonleads us to propose a greater seasonality as a possible cause. Considering the argu-able role of external abrasives on the microwear, another interpretation might involvethe presence of more grit in the eastern opener habitats. Interestingly, we found thatsympatric hipparionins tend to have similar feeding habits, which points to the fact thattheir diets were influenced by the local environment. Our results, then, suggest that thesmall size of some hipparionins resulted from different selective pressures rather thanto a general adaptation to increasing habitat openin