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The adaptive radiation of hipparionins after their Old World dispersal was linked with a trend towards smaller body sizes. The appearance of the small-sized forms has usually been associated to open environments and grazing diets. A recent approach, moreover, highlights the role of life history modifications related to habitat conditions as triggers of their size shifts. Here, we test the relationship between hipparionin size and diet analyzing the dental microwear textures of different-sized hipparionins from Vallesian and Turolian circum-Mediterranean localities. Our results show that hippari-onins were mainly mixed-feeders and that there was no general link between body size and diet. However, we identified broader feeding spectra in western Mediterranean smaller forms and more specialized grazing diets in larger ones, a differentiation not found in the eastern Mediterranean hipparionins. At odds with the notion of more open habitats eastward, we detected a larger browsing component in eastern hipparionin diets. The consumption by extant equids of more woody browse during the dry season leads us to propose a greater seasonality as a possible cause. Considering the argu-able role of external abrasives on the microwear, another interpretation might involve the presence of more grit in the eastern opener habitats. Interestingly, we found that sympatric hipparionins tend to have similar feeding habits, which points to the fact that their diets were influenced by the local environment. Our results, then, suggest that the small size of some hipparionins resulted from different selective pressures rather than to a general adaptation to increasing habitat opening., MCIN/AEI [PID2020-117118GBI00]; CERCA Program, Generalitat de Catalunya; Wenner-Gren International Collaborative Research Grant; Ege University [TTM/001/2015, TTM/001/2016]; AGAUR [2017 SGR 960]; FI-DGR 2016 grant - AGAUR (Generalitat de Catalunya) [2016FI_B00202]; Erasmus + fellowship; [SYN-THESIS ES-TAF-1846]; [CGL2015-63777], We would like to thank M. Fernandez and X. Aymerich for the molding of the material from the ICP (Institut Catala de Paleontologia Miquel Crusafont) . G.O-O. acknowledges the help received from F. Martin (PALEVOPRIM) during the obtainment of the DMT parameters and the posterior analyses. We further thank to D. Kostopoulos (Aristotle University of Thessaloniki) for his comments on the earlier versions of this manuscript. The editors (Y. Nakamura, A. Bush, and J.X. Samuels) and four reviewers including J. Saarinen are acknowledged for their helpful comments. Moreover, we would like to thank to the authorities of the following museum collections to give access to the related materials: Museo Nacional de Ciencias Naturales (MNCN), ICP museum, Laboratory of Geology and Palaeon-tology at the University of Thessaloniki, Palaeontological Museum Dimitar Kovachev at Asenovgrad, and the Ege University Natural History Museum. Funding for this study was provided by the Grant PID2020-117118GBI00 funded by MCIN/AEI/10.3039/501100011033 (M.K) , the project CGL2015-63777 (M.K) , and the CERCA Program, Generalitat de Catalunya. R.S.S., T.K., S.M., and G.M. were granted through a Wenner-Gren International Collaborative Research Grant (PIs: R.S. Scott and T. Kaya) to collect most of the Vallesian and Turolian equiddental molds from the eastern Mediterranean, and S.M. and T.K. were supported by the Ege University Research Projects TTM/001/2015 and TTM/001/2016. M.K. and G.O-O. were part of a research group recognized without funding by AGAUR (2017 SGR 960) and G.O-O. was supported by a FI-DGR 2016 grant (2016FI_B00202) awarded by AGAUR (Generalitat de Catalunya) and held an Erasmus + fellowship during his stay in the PALEVOPRIM laboratory (CNRS and University of Poitiers). The grant SYN-THESIS ES-TAF-1846 for the stay of J.C. at the MNCN of Madrid is also acknowledged.

The early Pleistocene is represented by a succession of glacial-interglacial cycles character-ized by a general tendency towards global cooling, with increasing aridity and seasonality.The large deer Eucladoceros is found in abundance in Europe during this period of faunaldispersions. The dietary plasticity of Eucladoceros and how it can mirror early Pleistoceneclimatic variations will be explored here using Dental Microwear Texture Analysis. Thewide range of dental microwear textures for Eucladoceros reflects a low selectivity and highplasticity in its diet. It is an appropriate proxy to track vegetal resource availability. Oscil-lations were identified between a browsing and a grazing signal. This study proposes thata browsing signal is associated with a fossil assemblage deposited during an interglacialevent characterized by warmer temperatures and deciduous vegetation. A grazing signalmore likely indicates a glacial event with cooler temperatures and a developed herbaceous,bushy layer. Le Pléistocène inférieur correspond à une succession de cycles glaciaires-interglaciairescaractérisée par une tendance générale au refroidissement global, avec une aridité et unesaisonnalité croissantes. Le cervidé de grande taille Eucladoceros est abondant en Europedurant cette période de dispersions fauniques. Grâce à l'analyse de texture de la micro-usuredentaire, nous explorons la plasticité alimentaire d'Eucladoceros et la manière dont celle-ci reflète les variations climatiques du Pléistocène inférieur. La large gamme de texturesde micro-usure dentaire d'Eucladoceros reflète sa faible sélectivité et sa forte plasticité ali-mentaire. De fait, il constitue un outil approprié pour aborder la disponibilité en ressources végétales dans le milieu. Nous identifions des oscillations entre un signal brouteur et unsignal paisseur. Nous proposons qu'un signal brouteur soit associé à un assemblage fossiledéposé lors d'un évènement interglaciaire caractérisé par des températures plus chaudeset une végétation décidue, tandis qu'un signal paisseur correspondrait plutôt à un évène-ment glaciaire, avec des températures plus froides et la présence d?une strate herbacée etarbustive développée. This project was supported by the “Agence nationale dela recherche” (ANR TRIDENT: grant number: ANR-13-JSV7-0008-01; PI.: Gildas Merceron).

International audience; Dental microwear has been used in paleoecology for nearly half a century. The advent of technologies in the past decade has allowed for enamel surfaces to be scanned in 3D, and thus for microwear textures to be characterized as a whole. Although dental microwear texture analysis is widely used, few studies have tackled the issue of sample representativity, or the variability of the microwear signal along a facet or a tooth row. How much information can we accurately extract from a fossil sample when tooth wear is considered? Can we accurately make inferences on a whole species based on fossil samples primarily comprised of isolated teeth? These matters remain to be characterized in a controlled setting. In this study, we tackle this issue from the ground up. A large-scale controlled food trial conducted on domestic sheep provides the framework in which to test these fundamental questions. Our results highlight that analyzing a 200 × 200 µm surface allows for better differentiation between dietary categories, as opposed to analyzing smaller surfaces. Comparisons of facets from upper and lower molars reveal significant variations depending on the contribution to either the buccal or the lingual shearing phase I during the chewing cycle. Investigating the microwear signal along the tooth row does not reveal any significant variation between molars belonging to a same tooth row. However, when simulating three fossil samples composed of isolated upper or lower molars from M1 to M3 from the three sets of ewes, our study does highlight poor results in discriminating dietary categories.

While grazing as a selective factor towards hypsodont dentition on mammals has gained a lot of attention, the importance of fruits and seeds as fallback resources for many browsing ungulates has caught much less attention. Controlled‐food experiments, by reducing the dietary range, allow for a direct quantification of the effect of each type of items separately on enamel abrasion. We present the results of a dental microwear texture analysis on 40 ewes clustered into four different controlled diets: clover alone, and then three diets composed of clover together with either barley, corn, or chestnuts. Among the seed‐eating groups, only the barley one shows higher complexity than the seed‐free group. Canonical discriminant analysis is successful at correctly classifying the majority of clover‐ and seed‐fed ewes. Although this study focuses on diets which all fall within a single dietary category (browse), the groups show variations in dental microwear textures in relation with the presence and the type of seeds. More than a matter of seed size and hardness, a high amount of kernels ingested per day is found to be correlated with high complexity on enamel molar facets. This highlights the high variability of the physical properties of the foods falling under the browsing umbrella.