Palaeontologia Electronica palaeo-electronica.org Feeding strategies of circum-Mediterranean hipparionins during the late Miocene: Exploring dietary preferences related to size through dental microwear analysis Guillem Orlandi-Oliveras, Meike Köhler, Julien Clavel, Robert S. Scott, Serdar Mayda, Tanju Kaya, and Gildas Merceron ABSTRACT 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. Guillem Orlandi-Oliveras. Institut Català de Paleontologia Miquel Crusafont (ICP), Edifici Z, carrer de les Columnes s/n., Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain. guillem.orlandi@icp.cat Meike Köhler. Institut Català de Paleontologia Miquel Crusafont (ICP), Edifici Z, carrer de les Columnes s/ n., Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain and Institució Catalana de Recerca i Estudis Avançats (ICREA), passeig Lluís Companys 23, 08010 Barcelona, Spain. meike.kohler@icp.cat Orlandi-Oliveras, Guillem, Köhler, Meike, Clavel, Julien, Scott, Robert S., Mayda, Serdar, Kaya, Tanju, and Merceron, Gildas. 2022. Feeding strategies of circum-Mediterranean hipparionins during the late Miocene: Exploring dietary preferences related to size through dental microwear analysis. Palaeontologia Electronica, 25(1):a13. https://doi.org/10.26879/990 palaeo-electronica.org/content/2022/3591-hipparionin-dental-microwear Copyright: April 2022 Palaeontological Association. This is an open access article distributed under the terms of Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0), which permits users to copy and redistribute the material in any medium or format, provided it is not used for commercial purposes and the original author and source are credited, with indications if any changes are made. creativecommons.org/licenses/by-nc-sa/4.0/ ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR Julien Clavel. Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69622, Villeurbanne, France. julien.clavel@univ-lyon1.fr Robert S. Scott. Department of Anthropology and Center for Human Evolutionary Studies, Rutgers, The State University of New Jersey, New Jersey 08901 New Brunswick, USA. robertsc@scarletmail.rutgers.edu Serdar Mayda. Department of Biology, Faculty of Science, Ege University, Bornova 35100, Izmir, Turkey and Natural History Museum, Ege University, Bornova 35100, Izmir, Turkey. serdar.mayda@ege.edu.tr Gildas Merceron. Laboratoire PALEVOPRIM, UMR 7262 CNRS and University of Poitiers, TSA 51106, 86073 Poitiers Cedex9, France. gildas.merceron@univ-poitiers.fr Keywords: Hipparion; Equidae; diet; body size; dental microwear texture analysis Submission: 13 April 2019. Acceptance: 4 April 2022. INTRODUCTION however, that the Old World hipparionin horses reached their highest taxonomic and ecological The living Equidae are today represented by diversity (Bernor et al., 1990a, 1996; Scott and only a few species from the genus Equus, which Maga, 2005; Merceron et al., 2016a). This diversifi- chiefly graze and inhabit open habitats (Bauer et cation is marked by an increase in the range of al., 1994; Moehlman, 2002). However, in the past body sizes, especially towards smaller sizes (Ber- the Equidae exhibited much greater taxonomic nor et al., 1996; Ortiz-Jaureguizar and Alberdi, richness (Woodburne and MacFadden, 1982; Mac- 2003). The “Cremohipparion clade” [sensu Bernor Fadden, 1992, 2005) and a broader spectrum of et al. (1996)], for instance, diversified along two dietary adaptations (MacFadden et al., 1999; Tüt- opposite trajectories; leading to the appearance of ken et al., 2013; Semprebon et al., 2016) more a lineage characterized by large-sized horses (e.g., comparable to modern African bovids (Gagnon and Cremohipparion proboscideum) and to the appear- Chew, 2000). Similarly, extinct equids occupied ance of other forms that decreased in body size more habitat types than their extant relatives (Mac- (e.g., Cremohipparion matthewi) (Bernor et al., Fadden, 1992; Semprebon et al., 2016) and 1996, 2016). Those hipparionins that decreased in showed a broader range of body sizes (MacFad- body size may have evolved the small size inde- den, 1992; Alberdi et al., 1995; Gould and Mac- pendently (Woodburne and MacFadden, 1982; Fadden, 2004). Bernor and Tobien, 1989). Hence, contrary to the Hipparionins are an equid tribe that was espe- commonly described phyletic size increase in Equi- cially diverse during the late Miocene, when its rep- dae, size decrease processes took place numer- resentatives were very abundant in many of the ous times during their evolutionary history mammal assemblages from the Holarctic realm (MacFadden, 1992; Gould and MacFadden, 2004). (Woodburne, 1989; Bernor et al., 1996). These The shift towards smaller size in some hippar- three-toed horses radiated soon after their first dis- ionins, together with their diversification, has been persal from North America to the Old World (Wood- associated with increasing climate seasonality and burne, 1989, 2009; Bernor et al., 1996, 2003; Scott its repercussions on floral communities (Bernor et et al., 2003; Cantalapiedra et al., 2017). Conse- al., 1990a, 1996; Saarinen, 2009). Accordingly, quently, sympatric and morphologically diverse some authors have suggested that the small-sized species are found in western and eastern Mediter- hipparionins dwelt in more open habitats (Bernor et ranean regions already during the beginning of the al., 1996, 2021; Saarinen, 2009) and were adapted Vallesian (Forsten, 1997; Scott et al., 2003; Kou- to forage on less nutritious xerophytic forage (For- fos, 2016) [European Land Mammal Age, 11.2–8.9 sten, 1968, 1978b). In the same way, small-sized Ma (Hilgen et al., 2012)]. Although the hipparionins Equus of the European Pleistocene have been from circum-Mediterranean regions underwent an suggested to inhabit open environments and to important taxonomic and morphological diversifica- consume less browse than larger forms (Saarinen tion (Forsten, 1968; Koufos, 1990; Bernor et al., et al., 2021). On the other hand, some authors 1990b, 1996), in central Europe the specific diver- have argued that the smaller hipparionin forms sity was much lower (Forsten, 1978a; Bernor et al., were adapted to more closed and forested areas 1990a). It is during the Turolian [European Land (Ortiz-Jaureguizar and Alberdi, 2003), like extant Mammal Age, 8.9–5.3 Ma (Hilgen et al., 2012)], 2 PALAEO-ELECTRONICA.ORG “smaller zebras” (Alberdi et al., 1995, p. 363). The explored. Due to 1) the long-time interval of hippar- hipparionin size diminution trends, moreover, have ionin presence in the Old World, 2) their wide geo- been associated with shifts in adult mortality graphical distribution, and 3) their broad range of regimes in some cases, and resource availability in body sizes, hipparionins constitute a good model others (Orlandi-Oliveras et al., 2018). These two for exploring size related niche partitioning with scenarios can also be indirectly linked to changes respect to habitat and feeding preferences across in habitat structure. closely-related ungulates. Animal body size is related to many physio- In previous studies, the hipparionin size dif- logical and ecological factors (Peters, 1983; ferences have been explored from a life history Calder, 1984; Palkovacs, 2003). One of the central approach by means of bone and dental histology variables determining body size is growth rate, analysis (Orlandi-Oliveras et al., 2018, 2019). In which in turn is strongly affected by the environ- this work, we first aim to evaluate the scaling rela- mental effects on food availability and foraging risk tionship between ecological preferences (diet) and (Dmitriew, 2011). Hence, the items consumed by hipparionin body size. The present study, hence, an animal do not only depend on the availability might help to test the interpretations on hipparionin and quality of the resources, but also on the com- paleobiology obtained from previous life history petitive pressure and predation risk associated with inferences. Moreover, the obtained data will also the exploitation of these resources (Brown, 1988). shed light on the dietary preferences of the studied In turn, these factors all depend on habitat type hipparionin groups as well as habitat differences and structure. A general relationship can thus be between the Mediterranean areas through the late described for body mass, diet, and habitat in extant Miocene. We therefore applied Dental Microwear African ungulates: large-sized species tend to Texture Analysis (DMTA) on teeth of different-sized inhabit open areas and graze on abundant low hipparionins from Vallesian and Turolian sites quality food, while smaller taxa generally browse located on eastern and western Mediterranean on less abundant high quality items in closed habi- basins, with special interest on sympatric taxa, to tats (Bell, 1971; Jarman, 1974; Case, 1979; Gag- infer their diet. DMTA has proven to be a powerful non and Chew, 2000; Hopcraft et al., 2010). tool for tracking fine grained differences in diet It was long assumed that hipparionins were such as seasonal variations on extant species and mostly open savanna grazers due to their high- has successfully been applied to fossil species crowned teeth (Matthew, 1926; Stirton, 1947; Steb- (Merceron, et al., 2009, 2021; DeSantis, 2016; Ber- bins, 1981; MacFadden and Hulbert, 1988). lioz et al., 2017; Martin et al., 2018; Hullot, et al., Because of that, their arrival to the Old World was 2019). Our results will help to understand the tentatively linked to the spread of grasslands dietary preferences of the hipparionins of diverse (Gabunia and Chochieva, 1982; MacFadden, size classes, and to explore the changes they went 1992), a thesis no longer supported by posterior through from Vallesian to Turolian in different areas studies on hipparionin diets (Hayek et al., 1992; of their distribution range. In this regard, we start MacFadden et al., 1999; Kaiser, 2003; Tütken et from a series of hypothesis. First, if the hipparionin al., 2013; Merceron et al., 2016a), by evidence of trend towards smaller body sizes represents adap- grassland presence predating their appearance tations to diet and habitat (cf. Forsten, 1978; Ber- (Strömberg, 2006; Strömberg et al., 2007), as well nor et al., 1990a, 1996), we could expect shared as a tree cover that may have been more dense as dietary strategies among small hipparionins from initially thought (Solounias, 1999). In this context, their DMT. Second, the hipparionin dietary signal while some studies have not identified significant can help us to identify paleoecological differences feeding differences between sympatric hipparionin between the western and eastern Mediterranean species (Solounias et al., 2010; Clavel et al., 2012; biomes, the latter is considered to have more open Rey et al., 2013), others detected dietary niche- habitats (cf. Bonis et al., 1992), as we could also partitioning between taxa (MacFadden et al., 1999; expect to identify changes on the floral associa- Merceron et al., 2016a). Similarly, life history strat- tions from the Vallesian to the more dry and sea- egies have also been found to differ between hip- sonal Turolian (cf. Fortelius et al., 1996). Finally, parionins of different sizes (Orlandi-Oliveras et al., this data might help to shed more light on the 2018, 2019). Although hipparionin dietary prefer- dietary behavior of the different hipparionin groups ences have been extensively studied from a paleo- analyzed, challenging the grazing specialization environmental point of view, the relationship due to their hypsodont dentition. between their size and diet has not yet been 3 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR MATERIAL AND METHODS within the proposed supraspecific groupings (Ber- nor et al., 1996). We organized the eastern Medi- Sample and Study Area terranean hipparionin taxa following the The fossil specimens come from 20 late Mio- morphotypes defined by Vlachou (2013). We cene fossil sites of circum-Mediterranean basins grouped the western Mediterranean hipparionins (Figure 1). We have focused on localities that considering size morphotypes, which follow spe- yielded large hipparionin assemblages and with cific differences, due to the general lack of com- those exhibiting a high hipparionin size diversity. plete cranial material. We predominantly sampled the more diverse Turo- Microwear Data Acquisition lian fossil sites. Far from being homogeneous, eastern Mediterranean faunas show some dissimi- The sample studied comprises 372 teeth from larities during most part of the Turolian (Kostopou- a wide range of hipparionin populations (Table 1; los, 2009; Koufos and Vlachou, 2016). We divided, Appendix 2). We discarded unworn and senile hence, the eastern Mediterranean Turolian sample specimens with very worn molars, together with in the western Anatolian (Samos island and conti- those that showed post-mortem alterations as nental western Anatolia) and the Balkans bioprov- observed on the microwear scans (see Calandra inces (continental Greece and Bulgaria). Vallesian and Merceron, 2016). We preferably selected sec- hipparionins come from western Mediterranean ond upper or lower molars, although in some cases and from the Balkans, while Turolian forms come we also analyzed first/third molars and third/fourth from the three bioprovinces studied (see Appendix premolars as variations in DMT along the tooth row 1 for detailed information). are not significant (Ramdarshan et al., 2017). Fol- Here we decided to use the broad sense of lowing standard procedures, the occlusal surfaces the genus Hipparion because of the lack of cranial of the teeth were cleaned using acetone-soaked material available for some of the analyzed taxa, cotton swabs to remove dust particles and glue. which hinders their unequivocal determination Afterwards, dental replicas were made using a FIGURE 1. Geographic distribution of the localities from western Mediterranean (circles), Balkans (stars), and western Anatolian (squares) basins. Dashed contours depicting the areas with Vallesian localities sampled. 1. Vallès-Penedès Basin (Santiga, Can Llobateres, Can Poncic); 2. Teruel Basin (Concud, El Arquillo); 3. Cabriel Basin (Venta del Moro); 4. Axios Valley (Pentalophos, Ravin de la Pluie, Ravin des Zouaves-5 and Dytiko sites); 5. Thessaly (Perivolaki); 6. Mesta Valley (Hadjidimovo); 7. Chalkidiki Peninsula (Nikiti-1 and Nikiti-2); 8. Biga Peninsula (Gülpınar); 9. Muğla Yatağan Basin (Şerefköy-2); 10. Samos Island (Mytilinii-A, Mytilinii-B). 4 PALAEO-ELECTRONICA.ORG TABLE 1. Descriptive statistics of each DMT parameter for all the hipparionin populations included in the present study. Mean body mass (BM) and the mean values of the textural parameters are also shown for each hipparionin group. Asfc = complexity, epLsar = anisotropy, HAsfc = heterogeneity of complexity calculated with a 64 cells mesh, Tfv = textural fill volume, N = sample size, sem = standard error of the mean. mean epLsar sem epLsar mean Asfc sem Asfc hipparionin mean BM Age Bioprovince group Size class Locality (kg) N ?primigenium Small Santiga 154d 13 2.00 0.34 3.28 0.51 Western Can Llobateres 194d 47 2.22 0.12 3.43 0.31 Mediterranean primigenium Large Can Poncic 205d 11 1.50 0.22 3.69 0.54 All 200 58 2.09 0.11 3.48 0.27 Vallesian Axios Vallesian 103e 4 2.96 0.56 3.30 0.49 macedonicum Small Nikiti-1 81e 2 1.86 0.16 3.13 0.49 All 92 6 2.59 0.43 3.25 0.34 Balkans Axios Vallesian 167e 12 2.78 0.46 3.88 0.60 primigenium Large Nikiti-1 214e 2 2.12 0.43 2.64 1.51 All 191 14 2.68 0.40 3.70 0.55 periafricanum Small El Arquillo 31d 17 2.30 0.45 2.89 0.31 gromovae Small El Arquillo 84f 34 1.80 0.16 3.56 0.28 Western cf. matthewi Large Venta del Moro 124g 20 1.17 0.13 4.81 0.42 Mediterranean concudense Large Concud 178g 24 1.16 0.09 5.39 0.38 primigenium Large El Arquillo 192f 5 1.78 0.54 4.35 1.05 Nikiti-2 76e 17 1.95 0.15 5.35 0.44 Ravin des 71e 11 2.75 0.20 4.10 0.68 Zouaves-5 macedonicum Small Perivolaki 73e 11 2.72 0.45 2.69 0.44 Turolian Dytiko sitesb 62e 6 2.38 0.46 2.65 0.67 All 71 45 2.39 0.15 4.03 0.32 Nikiti-2 113e 4 1.74 0.22 5.40 1.03 Balkans Perivolaki 127e 6 3.37 0.77 2.53 0.41 dietrichi Large Dytiko sitesb 144e 21 1.99 0.18 3.91 0.42 All 128 31 2.22 0.21 3.84 0.35 Ravin des 202e 1 2.00 - 5.44 - Zouaves-5 Hadjidimovo 183d 18 2.29 0.19 4.21 0.48 proboscideum Large Perivolaki 165e 1 2.11 - 3.27 - All 183 20 2.27 0.17 4.23 0.43 polyvinyl siloxane silicone of medium consistency metacone and hypoconid were selected when the (ISO 4823, President Regular Body, Coltène- former showed alterations. The lateral resolution Whaledent). These molds were scanned with the (x,y) of the scans was set to 0.129 μm, and the ver- “TRIDENT” Leica DCM8 white-light confocal profi- tical spacing to less than 0.002 μm. Once scanned, lometer (PALEVOPRIM lab CNRS University of the surfaces were saved as .plμ files by LeicaScan Poitiers, France) with a 100× lens (numerical aper- software (Leica Microsystems) and imported for ture = 0.90; working distance = 0.9 mm). We processing to LeicaMap following procedures scanned preferentially the lingual facets of shown in Merceron et al. (2016a). A 200 × 200 μm paracone and buccal facets of protoconid, but area was extracted and saved as a .sur file. All the 5 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR TABLE 1 (continued). mean epLsar sem epLsar mean Asfc sem Asfc hipparionin mean BM Age Bioprovince group Size class Locality (kg) N primigenium Large Hadjidimovo 256d 17 2.08 0.18 4.28 0.51 Gülpınar 81d 7 2.39 0.84 4.25 0.82 Şerefköy-2 83d 17 2.16 0.19 3.90 0.39 macedonicum Small Samos new 108e 3 1.95 0.81 3.29 0.62 Collectionc All 91 27 2.20 0.25 3.92 0.32 Turolian Western Gülpınar 161d 10 1.86 0.27 4.04 0.43 Anatolia Samos new dietrichi Large 201e 3 1.79 0.31 2.73 0.50 Collectionc All 181 13 1.85 0.22 3.74 0.37 Şerefköy-2 201d 19 2.01 0.16 3.88 0.44 Samos new proboscideum Large 238e 9 1.41 0.12 4.08 0.86 Collectionc All 220 28 1.82 0.12 3.95 0.40 Note: Fossil sites of Pentalophos and Ravin de la Pluie (a); Dytiko-1, Dytiko-2 and Dytiko-3 (b); Mytilinii A and Mytilinii B (c). Mean body mass estimations were based on metapodial measures and were calculated in this study (d) or obtained from: Vlachou (2013) (e), Orlandi-Oliveras et al. (2018) (f) and Pesquero and Alberdi (2012) (g). specimens were scanned and processed at Here we consider the heterogeneity of complexity PALEVOPRIM (CNRS and University of Poitiers, over 64 cells per scan, because this setting contrib- France). Photo-simulations of the surfaces ana- uted the most to the variance in our sample (tested lyzed are available in Appendix 3. via Principal Component Analysis, Appendix 4). Finally, a linear combination of all four dental Dental Microwear Texture Variables and microwear texture parameters was performed by Statistical Analyses means of a Principal Component Analysis. The The scans obtained from DMTA can be quan- most explicative principal component (PC1) has tified repeatably, limiting the risks for intra- and been used as a proxy of the overall microwear tex- inter-observer errors compared to other microwear ture, gathering the major variance from the four techniques (Ungar et al., 2003; Scott et al., 2005, DMT variables. Unfortunately, because extant 2006; DeSantis et al., 2013). The surfaces were equids are mostly grazers, there is no extensive processed using Toothfrax and Sfrax software dataset to which to compare the DMT of extinct (Surfract, http://www.surfract.com) applying Scale equids with that of extant forms with different diets. Sensitive Fractal Analysis (SSFA) and following the However, we considered a sample of wild standard procedures detailed in Scott et al. (2006). Burchell’s zebras and semi-wild asses from Iran as SSFA generates a set of Dental Microwear Texture comparative baseline (see Figure 2). Also, we (DMT) parameters that quantify the enamel sur- relied on the framework provided by Scott (2012) in face. These are described in Scott et al. (2005, which the DMT has been explored in relation to 2006). In the present study, we focused on the diet in another group of ungulates with much ones that better reflect surface textural attributes diverse dietary adaptations. correlated to diet: complexity (area scale fractal The DMTs of extant mammals have shown to complexity, Asfc), anisotropy (exact proportion of be correlated to the mechanical properties of the length scale anisotropy of relief at the resolution of food processed in their diet (hardness and tough- 1.8 µm, epLsar), heterogeneity of complexity with ness). This has proven to be true despite the an 8 × 8 mesh (heterogeneity of area scale fractal amount of exogenous abrasives present (Merceron complexity, HAsfc), and textural fill volume with et al., 2016b; Schulz-Kornas, et al., 2020; Acker- square edge set at 2 µm (Tfv) (Scott et al., 2006). mans, et al., 2020b; Hua, et al., 2020). The con- 6 PALAEO-ELECTRONICA.ORG TABLE 1 (continued). mean Tfv (µm²) sem Tfv (µm²) mean HAsfc sem HAsfc hipparionin mean BM Age Bioprovince group Size class Locality (kg) N ?primigenium Small Santiga 154d 13 0.605 0.052 48995 2309 Western Can Llobateres 194d 47 0.432 0.017 42658 1430 Mediterranean primigenium Large Can Poncic 205d 11 0.485 0.028 43019 1683 All 200 58 0.442 0.015 42726 1196 Vallesian Axios Vallesian 103e 4 0.426 0.082 46358 5055 macedonicum Small Nikiti-1 81e 2 0.388 0.061 51683 444 All 92 6 0.414 0.055 48133 3390 Balkans Axios Vallesian 167e 12 0.388 0.022 43898 2136 primigenium Large Nikiti-1 214e 2 0.510 0.008 42243 8015 All 191 14 0.405 0.022 43662 2010 periafricanum Small El Arquillo 31d 17 0.579 0.080 43353 1868 gromovae Small El Arquillo 84f 34 0.488 0.029 42824 1545 Western cf. matthewi Large Venta del Moro 124g 20 0.434 0.024 46778 2079 Mediterranean concudense Large Concud 178g 24 0.431 0.026 43961 2193 primigenium Large El Arquillo 192f 5 0.361 0.037 43050 4220 Nikiti-2 76e 17 0.412 0.020 42982 1855 Ravin des 71e 11 0.475 0.047 41073 2247 Zouaves-5 macedonicum Small Perivolaki 73e 11 0.467 0.063 43848 2025 Turolian Dytiko sitesb 62e 6 0.480 0.049 50561 2518 All 71 45 0.450 0.021 43738 1124 Nikiti-2 113e 4 0.454 0.048 40964 3888 Balkans Perivolaki 127e 6 0.472 0.042 44124 2455 dietrichi Large Dytiko sitesb 144e 21 0.503 0.037 41592 2649 All 128 31 0.491 0.027 42001 1896 Ravin des 202e 1 0.356 - 27397 - Zouaves-5 Hadjidimovo 183d 18 0.585 0.038 38219 2153 proboscideum Large Perivolaki 165e 1 0.454 - 55049 - All 183 20 0.567 0.036 38519 2187 sumption of tough food—such as mature Calandra and Merceron, 2016). Therefore, the grasses—tends to produce high anisotropic tex- dietary ecology of extinct taxa can be revealed by tures, whereas the processing of harder and more means of their dental microwear textures. brittle items—such as woody browse—results in Correlation between body size and diet. Body textures of lower anisotropy indices and high com- mass estimates have been used as a measure of plexities. Generalists and mixed-feeders consume body size (Damuth and MacFadden, 1990). We diverse types of resources with varying mechanical compiled from the literature body mass estimations properties, which it appears to increase the hetero- based on metapodial measures (Pesquero and geneity of the texture complexity (see review in Alberdi, 2012; Vlachou, 2013; Orlandi-Oliveras et 7 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR TABLE 1 (continued). mean Tfv (µm²) sem Tfv (µm²) mean HAsfc sem HAsfc hipparionin mean BM Age Bioprovince group Size class Locality (kg) N primigenium Large Hadjidimovo 256d 17 0.620 0.056 42308 1859 Gülpınar 81d 7 0.629 0.044 47139 3881 Şerefköy-2 83d 17 0.379 0.031 41791 2002 macedonicum Small Samos new 108e 3 0.546 0.058 34852 7100 Collectionc All 91 27 0.462 0.031 42407 1833 Turolian Western Gülpınar 161d 10 0.584 0.056 44344 1751 Anatolia Samos new dietrichi Large 201e 3 0.452 0.043 38931 2359 Collectionc All 181 13 0.553 0.046 43095 1554 Şerefköy-2 201d 19 0.432 0.018 42361 2169 Samos new proboscideum Large 238e 9 0.409 0.017 34554 3009 Collectionc All 220 28 0.425 0.013 39852 1866 al., 2018), and calculated our own estimations small-sized hipparionins (Alberdi, 1989; Bernor, et using published data (Forsten and Kaya, 1995; al., 1996). However, despite surpassing the 100 kg Clavel et al., 2012) and own measures (Appendix threshold, we included into the small group the 5). Calculations were performed using equations medium- to small-sized Hipparion sp. from the from Scott (1990) and Eisenmann and Sondaar western Mediterranean early Vallesian (Forsten, (1998). We tested the link between the hipparionin 1997) (154 kg), the Hipparion macedonicum from size and their dietary preferences using linear least the Axios Valley Vallesian (103 kg), and the H. cf. squares regressions: mean body mass estimates matthewi from Samos (108 kg), by considering the per population were correlated to our obtained larger body masses of their sympatric taxa (Table dietary proxies [i.e., each DMT variable and the 1), and that these groups represent the smallest calculated principal component (PC1)]. forms present in their associations (Appendix 1). Dietary differences between hipparionin popu- Thus, the body mass of the large members from lations. While considering the size differences, we the eastern Mediterranean ranges from 113 kg to have further explored the dietary diversity shown 281 kg, while in the small taxa range from 62 kg to among hipparionins through time and space. In this 108 kg. In the western Mediterranean, the body regard, eastern and western Mediterranean hippar- mass of the large hipparionins goes from 124 kg to ionins were differentiated, divided depending on 205 kg, and from 31 kg to 154 kg (84 kg, excluding the age of the fossil association (Vallesian/Turo- the early Vallesian form) in the small members. lian), and separated by their size category. Our To explore the variation on the dental smallest “work unit” was hipparionin population, microwear texture related to regional, chronologi- which we defined as each group present in a spe- cal, and body size factors, a first set of analyses cific fossil locality. The mean body masses esti- based on three-way ANOVAs were performed for mates of the sampled populations range from 31 each DMT parameter. Post-hoc pairwise compari- kg (periafricanum group from El Arquillo) to more sons tests, the Tukey’s Honest Significant Differ- than 250 kg (primigenium group from Hadjidimovo) ences test (HSD) and the less conservative (Table 1). We used a 100 kg threshold to establish Fisher’s Least Significant Differences test (LSD), two body size categories, dividing the large- to were then used in tandem to identify the source of medium-sized hipparionins (> 100 kg), and the variation. These parametric procedures were small-sized ones (< 100 kg), which separates quite applied to rank-transformed variables for approxi- well the forms considered by previous authors as mating distribution free (e.g., non-parametric) tests 8 PALAEO-ELECTRONICA.ORG FIGURE 2. Bivariate plot showing the mean and the standard error of the mean for the complexity (Asfc) and anisot- ropy (epLsar) variables. The symbol type (circle/square) represents the region, the filling of the symbol differentiates between hipparionin size types, and the color if they are from Vallesian (grey) or Turolian (black) assemblages. Extant wild Equus africanus asinus (A) and Equus quagga burchelli (B) are included for comparison. (Conover and Iman, 1981). Facing unbalanced fac- and LSD were used as post-hoc tests, and all the torial designs, here we used Type II sums of variables were rank-transformed prior to the analy- squares (SS) because it has been proved to be ses. A significance level of α = 0.05 has been used more powerful than Type III SS and does not for all tests. depend on the arbitrary order of the model terms (Langsrud, 2003). Because marginality principle RESULTS applies to multifactorial ANOVA designs (Nelder, Relationship between Hipparionin Diet and Size 1977; Langsrud, 2003), the significance of the main effects was only interpreted when the interac- The first principal component (PC1) built with tion term was insignificant. the four DMT variables, and considered as a more Moreover, a second set of analyses consisting direct dietary proxy, gathered 34.6% of the total in three-way nested ANOVAs were performed to variance (Table 2). The variance of this PC1 is explore in more detail the hipparionin dietary chiefly explained by complexity (Asfc, 45.2%), regimes during the Turolian, when this clade anisotropy (epLsar; 28.5%), and heterogeneity of achieved its higher taxonomic and size diversity. complexity (HAsfc; 26.3%), whereas textural filled Here, we tested for differences on the dental volume (Tfv) accounts for less than the 0.1% of it. microwear textures between the three bioprovinces Anisotropy is positively correlated with this princi- surveyed (western Mediterranean, Balkans and pal component, while Asfc, HAsfc, and Tfv are neg- western Anatolia) and the hipparionin groups pres- atively correlated. Hence, higher PC1 values are ent within these areas (Appendix 1), while also linked to less complex enamel surfaces, which in considering the localities in which these groups are turn are more anisotropic and homogeneous, and present. Differences were tested on the four DMT have smaller microwear features; traits which are variables and on our calculated PC1. Again, HSD typically shown by tough leaf browsing species, 9 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR TABLE 2. Results of the Principal Component Analysis performed with the four DMT variables. Percentage of variance explained by the principal component and contribution of each variable to the principal components are shown. r: cor- relation coefficient between the DMT variables and the principal components; r2: proportion of variance of the principal component explained by each variable. Asfc epLsar HAsfc Tfv % of cumulative % Component variance of variance r r2 r r2 r r2 r r2 PC1 34.58 34.58 -0.672 0.452 0.534 0.285 -0.513 0.263 -0.023 0.001 PC2 25.16 59.73 0.083 0.007 0.138 0.019 -0.010 0.000 0.987 0.974 PC3 23.26 83.00 -0.023 0.001 0.673 0.453 0.735 0.540 -0.084 0.007 PC4 17.00 100 -0.735 0.540 -0.493 0.243 0.444 0.197 0.135 0.018 and most especially, grazing species (Hedberg and from the Vallesian to the Turolian in the large hip- DeSantis, 2017; Merceron et al., 2021). The parionins, but not for smaller ones (Table 5), which regressions of this PC1 and the four microwear maintain high levels of complexity during the Turo- textural parameters with the hipparionin body mass lian (Figure 2). Moreover, complexity is generally show no significant correlation (Table 3, Appendix higher in the eastern hipparionins compared to the 6). Thus, there seems to be no general relationship western groups (Figure 2). Anisotropy (epLsar), on between the microwear signal and the hipparionin the other hand, increases from Vallesian to Turo- body mass when all the complete sample is con- lian in both regions (Table 4; Figure 2). In the west- sidered. However, some significant correlations are ern Mediterranean, the small-sized hipparionins detected when separating the three bioprovinces. show significantly lower anisotropy (epLsar) values Heterogeneity of complexity (HAsfc) is negatively than the larger forms, while in the east the means correlated with hipparionin body mass in western between both size groups are similar (Table 6; Fig- Mediterranean (p < 0.01), while it is positively cor- ure 2). The western Mediterranean small hippari- related in the Balkans sample (p < 0.01) (Table 3). onins have also higher values of heterogeneity of Moreover, the PC1 is positively correlated with the complexity (HAsfc) than the large-sized forms from hipparionin body mass in the western Mediterra- the same region. In the eastern Mediterranean, we nean area (p = 0.03). In all cases, there is a high detect the opposite trend, since large-sized spe- dispersion of the data—with R2 always below 0.05 cies show higher HAsfc than the smaller ones (Table 3)—because the dependent variables (DMT (Table 6; Figure 3C). Heterogeneity of complexity parameters) show high variability as individual data also tends to increase from the Vallesian to the are considered, whereas the independent variable Turolian in hipparionins from eastern basins, while (mass) is represented by mean values per each it does not vary in the western area (Table 7; Figure population. The low R2 values may hinder interpre- 3C). Finally, the textural fill volume (Tfv) of the tations, but from these results we can elucidate a small Vallesian forms is higher than that of the trend that can be further explored through the sub- larger Vallesian ones, a trend that is not followed sequent analyses. during the Turolian (Table 5; Figure 3D). Spatial and Temporal Dietary Variations Related Hipparionin Diets during the Turolian to Hipparionin Size Nested ANOVAs on the more diverse Turolian In our first model we test whether three fac- sample show that the microwear patterns differ tors—geological age, geographic region, and body between hipparionin groups within the same bio- size—contribute to the variance of the dental province, and between the hipparionin populations microwear texture and might have influenced the within the same group (Table 8). Moreover, differ- hipparionin diet. Our results confirm that these ences on the Asfc and HAsfc between the three three factors explain the variations in dental bioprovinces are detected. In this regard, complex- microwear textures, being in many cases involved ity (Asfc) values are generally higher in the Balkans in significant interactions (Table 4). Hence, than in western Anatolia, while western Mediterra- changes in the dental microwear textures due to nean hipparionins show the lowest complexities one of these factors follow different directions (Appendix 7.1). Differences in heterogeneity of depending on a second factor. We detect a signifi- complexity (HAsfc) are only significant between the cant decrease on the complexity parameter (Asfc) Balkan sample and the less heterogeneous 10 PALAEO-ELECTRONICA.ORG TABLE 3. Summary of the linear regressions of the DMT parameters and the calculated principal component (PC1) against body mass. Graphs available at Appendix 6. Asfc epLsar HAsfc Tfv PC1 Summary Linear Regressions p-value R2 p-value R2 p-value R2 p-value R2 p-value R2 All Data 0.084 0.008 0.185 0.005 0.901 <0.001 0.087 0.008 0.116 0.007 Western 0.601 0.002 0.125 0.014 0.006 0.044 0.889 <0.001 0.028 0.028 Mediterranean Balkans 0.328 0.007 0.591 0.002 <0.001 0.010 0.121 0.018 0.449 0.004 Western Anatolia 0.121 0.036 0.990 <0.001 0.526 0.006 0.169 0.029 0.204 0.024 TABLE 4. ANOVA results for rank-transformed textural variables. Significant differences highlighted in bold. Asfc epLsar Source of Variance df SS F p-value df SS F p-value Age 1 295805 30.229 < 0.001 1 151118 13.777 < 0.001 Region 1 506330 51.743 < 0.001 1 8926 0.814 0.368 Size 1 92512 9.454 0.002 1 78955 7.198 0.008 Age x Region 1 22074 2.256 0.134 1 17151 1.564 0.212 Age x Size 1 80214 8.197 0.004 1 29078 2.651 0.104 Region x Size 1 32516 3.323 0.069 1 110058 10.034 0.002 Error 365 3571703 365 4003657 HAsfc Tfv Source of Variance df SS F p-value df SS F p-value Age 1 2 0.000 0.990 1 2482 0.220 0.639 Region 1 2396 0.221 0.639 1 31786 2.820 0.094 Size 1 306 0.028 0.867 1 32824 2.912 0.089 Age x Region 1 113296 10.432 0.001 1 16282 1.444 0.230 Age x Size 1 27647 2.546 0.111 1 75853 6.729 0.010 Region x Size 1 160919 14.818 < 0.001 1 29595 2.625 0.106 Error 365 3963924 365 4114613 Note: df: degree of freedom; SS: Sum of Square; F: F-statistic microwear signatures of the western Mediterra- the Balkans hipparionins are also detected in the nean hipparionins (Appendix 7.2). inter-group comparisons, since some groups (e.g., Turolian hipparionin groups significantly differ macedonicum and proboscideum) show minor in all parameters but Tfv (Table 8). The most nota- Asfc differences compared to other forms from ble differences are found between two large-sized western Anatolia and the western Mediterranean groups from the western Mediterranean (concu- (Figure 3A; Appendix 7.3). Other significant differ- dense and cf. matthewi) and the rest (Figures 3, 4; ences are found between the large-sized probosci- Appendix 7.3). Their dental microwear textures are deum and primigenium groups from the Balkans less complex (low Asfc) and tend to be more aniso- compared to other hipparionins that have lower tropic (high epLsar) and homogeneous (low HAsfc) heterogeneity values (HAsfc) (Figure 3C; Appendix than in other hipparionins (Table 1; Figure 3; 7.3). These inter-group dissimilarities apart, the Appendix 7.3), showing, hence, higher PC1 scores locality from which the samples came from is also (Figure 4). The general higher complexity values of an important factor affecting the variance of our 11 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR TABLE 5. Summary of post-hoc results on Region-Size interaction. DMT parameters rank-transformed before analy- sis. The name of the parameter is shown if the difference were significant. When both LSD and HSD detect significant differences, the name of the parameter is shown in bold. Vallesian Turolian Age x Size Interaction Small Large Small Large Vallesian Small Large Tfv Turolian Small Tfv Large Tfv Asfc Asfc TABLE 6. Summary of post-hoc results on Region-Size interaction. DMT parameters rank-transformed before analy- sis. The name of the parameter is shown if the difference were significant. When both LSD and HSD detect significant differences, the name of the parameter is shown in bold. Western Mediterranean Eastern Mediterranean Region x Size Interaction Small Large Small Large Western Small Mediterranean Large epLsar, HAsfc Eastern Small HAsfc Mediterranean Large epLsar HAsfc HAsfc sample (Table 8). Focusing on the groups present between body mass and diet type in extant African in more than one locality, pairwise comparisons herbivores (Codron et al., 2007), and even between fossil sites show that there are minor dif- between their body mass and the quality of the for- ferences in DMT parameters between populations age they ingest (De Iongh et al., 2011). A lack of (Appendices 7.4–7.7). Most of these dissimilarities association between size and diet has also been are caused by the high epLsar values of Nikiti-2 found in Pleistocene ungulates (Saarinen et al., macedonicum and dietrichi morphotypes in com- 2016) and in Eocene brontotheres (Mihlbachler parison with other populations from the same and Solounias, 2002). Similarly, our results show groups; together with the higher HAsfc values from that there is no evidence to support a general link Gülpınar and Hadjidimovo hipparionins (Table 1; between hipparionin size and their dietary prefer- Appendices 7.4–7.7). On the other hand, when ences at a global scale. However, at a regional considering the localities with sympatric taxa, no scale we still detect 1) an effect of size on the den- significant differences are found among forms tal microwear texture and 2) a slight coupling coexisting on the same fossil site (Appendices 7.8– between the hipparionin body size and the hetero- 7.15). Only some minor variations are detected geneity of complexity of their dental microwear tex- inside El Arquillo locality, with higher heterogeneity tures. This later tendency, however, follows (HAsfc) values in the small-sized periafricanum opposite directions: in the Balkans the small hippa- and gromovae hipparionins compared to that of the rionins’ diets were less generalized than those of larger primigenium group (Figure 3C; Appendix the larger species, while western Mediterranean 7.15). small forms fed on wider spectra of preferred items. Moreover, the small hipparionins from the DISCUSSION western Mediterranean consumed fewer tough items than the larger taxa, a trend not found in the Paleoecology of Hipparionins in Relation to eastern groups. Accordingly, there is a significant Their Size decrease in the grazing behavior related to the size The linkage between body size and dietary decrease in western Mediterranean, but not in the strategy is a matter still debated in extant ungu- other bioprovinces. These biogeographical differ- lates (Codron et al., 2007; De Iongh et al., 2011). ences within size groups strengthen the idea of no Contrary to previous interpretations (Bell, 1971; general correlation between diet and hipparionin Jarman, 1974; Gagnon and Chew, 2000), more size. recent studies failed to detect a correlation 12 PALAEO-ELECTRONICA.ORG FIGURE 3. Bar charts with the mean and the standard error of the mean of the four DMT parameters for each hippari- onin group. Small-sized forms shown in light grey, larger ones in dark grey. A: Asfc. B: epLsar. C: HAsfc. D: Tfv 13 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR TABLE 7. Summary of post-hoc results on Age-Region interaction. DMT parameters rank-transformed before analysis. The name of the parameter is shown if the difference were significant. When both LSD and HSD detect significant dif- ferences, the name of the parameter is shown in bold. Western Mediterranean Eastern Mediterranean Age x Region Interaction Vallesian Turolian Vallesian Turolian Western Vallesian Mediterranean Turolian Eastern Vallesian Mediterranean Turolian HAsfc TABLE 8. Nested ANOVA results for rank-transformed textural variables and PC1 of Turolian taxa. Significant differ- ences highlighted in bold. Asfc epLsar HAsfc Source of Variance df SS F p-value df SS F p-value df SS F p-value Bioprovince 2 297866 29.200 < 0.001 2 5116 0.435 0.648 2 35666 3.132 0.045 Group 9 137469 2.995 0.002 9 162174 3.065 0.002 9 185064 3.611 < 0.001 (Bioprovince) Locality 11 97747 1.742 0.065 11 164959 2.551 0.004 11 159116 2.540 0.005 (Group) Error 258 1315898 258 1516729 258 1469134 Tfv PC1 Source of Variance df SS F p-value df SS F p-value Bioprovince 2 27124 2.129 0.121 2 125488 11.502 < 0.001 Group 9 50479 0.881 0.543 9 199755 4.069 < 0.001 (Bioprovince) Locality 11 128135 1.829 0.050 11 116326 1.939 0.035 (Group) Error 258 1643242 258 1407411 Note: df: degree of freedom; SS: Sum of Square; F: F-statistic Paleoenvironmental inferences should prefer- finding that many hipparionin taxa were mixed- ably be based on the dietary habits of a broad feeders, so they could have dwelled both in more range of ungulates rather than from the diets of a forested or open bushy habitats. As the small-sized reduced group of them. Nevertheless, the opportu- forms analyzed seem to not strictly have similar nistic feeding habits of at least some hipparionins dietary regimes (thus, probably occupying different (Tütken et al., 2013), and the fact that their dietary types of landscapes) our results seem to indicate strategies are related to the available vegetation that the vegetation composition might has not and, thus, to the habitat properties (Kaiser, 2003), directly affected their body size. Other physiologi- allows us to get a broad idea of the environment in cal, ecological, and life history factors may have which these hipparionins might have dwelt. Con- had a significant influence on the size decrease sidering the absence of a global relationship trends undergone by some hipparionins (Orlandi- between size and diet, we suggest that there could Oliveras et al., 2018) and other equids (Saarinen et be no general correspondence between hippari- al., 2016, 2021). At a regional scale, however, onin size and their habitat preferences. However, western Mediterranean small taxa seem to be further habitat proxies might be necessary to make related to wider dietary spectra and, during the Tur- finer interpretations on the habitats of the different- olian, to more browsing diets compared to that of sized hipparionin forms, especially considering the their larger counterparts. Therefore, we infer that 14 PALAEO-ELECTRONICA.ORG FIGURE 4. Mean values and confidence intervals (2x standard error of the mean) of the microwear Principal Compo- nent 1 for each hipparionin group. Dashed lines used for small-sized groups and continuous for large-sized. Grey color represents Vallesian hipparionins and black color the Turolian hipparionins. these smaller hipparionins probably preferred more seasonally may have contributed to the observed heterogeneous and somewhat denser habitats. higher anisotropy in the Turolian forms. In the east- Small eastern Mediterranean hipparionins, on the ern Mediterranean, besides, hipparionins generally other hand, have similar microwear textures to differed from Vallesian to Turolian by the broaden- those of the larger species, suggesting that they ing of their diets, which were already based on might have occupied comparable niches. mixed-feeding strategies. This dietary niche expan- sion suggests the prevalence of mosaic habitats Temporal and Biogeographical Differences in that allow the exploitation of food resources with Hipparionin Diets diverse physical properties. Recent isotopic stud- The study of the dietary strategies of the cir- ies did not detect a major climate nor habitat cum-Mediterranean hipparionins further allows us change during the Vallesian-Turolian transition in to compare their feeding preferences and potential this area (Merceron et al., 2013; Rey et al., 2013), habitats through time and space. In this regard, the but only a slight decrease in the precipitation eastern Mediterranean habitats are supposed to be regime (Rey et al., 2013). However, Böhme et al. more open than those from the western side (Bonis (2008, 2011) have shown more severe variations in et al., 1992; Koufos, 2006), while a general trend of environmental conditions through Europe during increasing seasonality and habitat opening has the late Vallesian and at the Vallesian/Turolian been suggested in all the Mediterranean area from transition. Wider seasonal variations and more per- Vallesian to Turolian (Fortelius et al., 1996), a pat- turbations during the Turolian, could then have tern which is corroborated with ectotherms verte- enhanced the presence of heterogeneous land- brates (Böhme et al. 2008, 2011). These latter scapes with grasses, bushes, and shrubs (Merce- temporal changes have been linked to an increase ron et al., 2005a, 2016a; but see Solounias et al. of xerophytic vegetation and the development of 1999), that would have provided a high variety of open landscapes with a rich herbaceous layer that resources, including both browse and graze. This includes grasses (Agustı́ et al., 2003; Jiménez- diversity might have favored the coexistence of Moreno et al., 2007). The xerophytic foliage with diverse hipparionin taxa, which do not strongly dif- thicker epidermis and grasses at least available 15 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR fer in dietary strategies (Solounias et al., 2010) as supplies also point towards an expansion of the our results suggest. dietary regimes and the inclusion of more browse Broadly, the main differences between regions material (Winkler et al., 2013; Smith and DeSantis, lie in the different patterns observed through the 2018). It is during the drought periods in seasonal hipparionin size range (see previous section), and climates with harsh dry seasons that the herba- the more complex dental microwear textures of ceous layer and notably monocots are deeply eastern hipparionins compared to western forms. impoverished, as their radicular net does not go Therefore, compared to western Mediterranean deep enough to access water resources. There- hipparionins, the Balkans groups have dental fore, the increase in the browsing behavior of hip- microwear textures suggesting broader diets that parionins during these periods may be related to include items of harder nature, a dietary regime the seasonal depletion of herbaceous monocotyle- compatible with a more mixed-feeding strategy. As dons due to their lower water competitive capacity stated, the eastern Mediterranean is typically sup- compared to bushes, shrubs, and herbaceous posed to be more arid and less wooded than the dicots whose roots go deeper in soil (Hipondoka et western realm during the late Miocene, based on al., 2003; Wang et al., 2010; Donzelli et al., 2013; the comparison of the fossil mammal assemblages February et al., 2013). Once rains are back, then, (Bonis et al., 1992; Koufos, 2006) and to other herbaceous are more reactive to gain water proxies that point to the open character of the east- (Hipondoka et al., 2003; Scheiter and Higgins, ern habitats (Merceron et al., 2005a, 2010, 2016a; 2007). Keeping in mind how monocots and dicots Ioakim and Koufos, 2009; Koufos et al., 2009; access to water resources, the absence of strictly Strömberg et al., 2007; Rey et al., 2013). Hence, grazing hipparionins in the eastern Mediterranean the eastern Mediterranean biotope has mainly is not surprising. Besides, finding the most grazing been characterized by an open dry savanna with a hipparionins in the western Mediterranean makes rich layer of grasses and with some bushes and sense as well, since water shortages might be less shrubs (Merceron et al., 2005a, 2016a; Koufos et severe and thus monocots might have remained al., 2009), although other proxies suggest the exis- more abundant all around the year, especially at tence of more densely wooded areas (Solounias et places where flooding or megaherbivores stop the al., 1999, 2010; Denk, 2016; Denk et al., 2018). In growth of a bushy/tree layer. The more humid con- this context, we might have expected more grazing ditions near lakes and floodplains can, moreover, feeding strategies in the eastern Mediterranean support a richer layer of herbaceous vegetation taxa compared to western ones. (Rodgers, 1982), which is more present in the diets On the contrary, the large hipparionins from of our large western Mediterranean hipparionins. the Turolian western Mediterranean are the spe- Indeed, the populations that show a stronger graz- cies that grazed more, while eastern hipparionins ing signal (Hipparion concudense from Concud, have microwear textures consistent with the con- and Hipparion cf. matthewi from Venta del Moro) sumption of harder items (higher complexities) of come from fossil associations developed on lacus- diverse physical properties. We might interpret this trine environments (Montoya et al., 2006; Pes- pattern as a consequence of seasonal dry condi- quero et al., 2013). Hipparionin obligate grazers, tions given the open character of the eastern Medi- hence, were rather rare and probably inhabited terranean habitats, and that the late Miocene somewhat humid environments and/or faced sea- environments were arguably subject to significant sonal migrations. Similarly, the extant zebra spe- precipitation shifts (Merceron et al., 2005b, 2013). cies that graze more (Equus quagga and Equus Indeed, during the dry seasons, extant African zebra) are in turn those which undergo larger ungulates widen their dietary niches thus following migrations and are more water-dependent (Bell, less strict grazing diets (De Iongh et al., 2011). 1971; Estes, 1991; Moehlman, 2002). Accordingly, extant equids tend to include higher Besides the physical properties of the food quantity of harder woody browse in their diets and its phytolith content, the dental wear of ungu- during periods of low food availability due to late teeth has been related to the action of exoge- drought (Estes, 1991; Moehlman, 2002). The lower nous particles of grit and dust (Sanson et al., 2007; selective behavior and higher intake rates of the Lucas et al., 2014; Madden, 2014). The role of hindgut fermenters (Janis, 2008) can facilitate the these particles on the microwear signal is an issue broadening of their diets and compensate for the still debated, mostly because they are diverse in resource fluctuations. Moreover, studies on fossil nature, hardness, dimension, shape, density, and mammals coping with instable or limited resource periodicity (Merceron et al., 2016b; Schulz-Kornas 16 PALAEO-ELECTRONICA.ORG et al., 2020). On one hand, some studies have pean Vallesian (Kaiser, 2003; Tütken et al., 2013). highlighted the fact that their presence does not Accordingly, we show that the Vallesian forms ana- significantly alter the dietary signal of the DMT lyzed here were intermediate feeders. Within each (Burgman et al., 2016; Merceron et al., 2016b; region, the coexisting different-sized Vallesian hip- Adams et al., 2020). On the other hand, other parionins did not strongly differ in dental microwear experiments have demonstrated that grit particles textures, supporting quite similar feeding habits, of different size can have an influence on the except for the broader dietary spectra of the DMTA parameters (Ackermans et al., 2020b; smaller western Mediterranean forms. In this case, Schulz-Kornas et al., 2020). Actually, the inclusion they followed a more generalist diet than the larger of dust (simulating natural abundance with diame- hipparionins of the same area, including a wider ter below 100 µm) has shown to not increase the range of preferred items in a weekly basis, sug- complexity of the microwear texture most likely gesting different habits between these groups. On because those particles actually mimic phytoliths of the other hand, the primigenium and the macedon- biosilica (Merceron et al., 2016b). However, larger icum hipparionins from the eastern Mediterranean sand particles of millimetric grit could have an Vallesian show similar dietary preferences, consis- impact on microwear through the generation of tent with their comparable enamel carbon isotopes large pits (Solounias and Semprebon, 2002), so (Rey et al., 2013). We may then suggest that these arguably increasing complexity (Hedberg and groups had similar preferences of feeding habits DeSantis, 2017). Indeed, recent studies have and possibly habitats preferences. Compared shown that the size of the grit particles have a between regions, the dental microwear textures of stronger effect than their concentration (Acker- large-sized primigenium hipparionins are more mans et al., 2020b; Schulz-Kornas et al., 2020), complex in the eastern than in the western Mediter- and that the processing of large grit particles can ranean Vallesian, consistent with the general pat- result in higher DMT complexities (Ackermans et tern observed comparing both areas (see previous al., 2020b). Nevertheless, at least among rumi- section). However, this contrasts with a previous nants, rumen acts as a washing mechanism, which mesowear study that suggests a more browsing allow rumination free of large grit particles as they diet in the western Mediterranean primigenium decant by gravity at the bottom of the dietary bolus. forms compared to those of the east (Scott et al., Hipparionins, however, did not have this washing 2013). This disagreement can be related to the dis- mechanism. For this reason, it could be possible to tinct time scales addressed with the meso- and the relate the higher complexity of the DMTs of the microwear studies (Davis and Pineda-Munoz, eastern Mediterranean hipparionins to the higher 2016). On one hand, the mesowear signal might presence of grit in their drier opener environments illustrate the long-term feeding preferences (Acker- compared to those of the western Mediterranean. mans et al., 2020a) of the hipparionins due to The dietary reconstructions proposed here closer habitats in the west and opener habitats in potentially reflect the last weekly to monthly prefer- the east (Koufos, 2006; Scott et al., 2013). On the ences, due to the nature of the dental microwear other hand, our shorter term dental microwear studies (Teaford and Oyen, 1989; Teaford et al., results might reveal the seasonal addition of wood- 2017). On the other hand, long-term feeding strate- ier browse due to a stronger seasonal depletion of gies can be reached from mesowear and isotopic monocot resources in the eastern Mediterranean analyses when serial sampling is privileged, which or the higher presence of large grit particles in the can provide other comparative proxies for diet and more open environment eastwards. Another overcome possible caveats. The short-term nature provocative alternative would be to consider molar of microwear studies could represent a limitation, mesowear relief and cusp shape are not only so future paleoenvironmental studies comparing dependent from the proportion of silica bearing both regions might require the study of diverse plants in diet but also from the proportion of fibrous ungulate groups, together with the inclusion of iso- component (lignin, cellulose) in the dietary bolus. topic and/or mesowear data that complements the Besides, the grit presence could also have contrib- information obtained from the microwear texture. uted. When we focus on the diverse Turolian hippa- Diets of Hipparionin Groups and Populations rionin assemblages, the greatest differences are Previous studies have suggested a mixed- found when comparing the large-sized western hip- feeding and opportunistic dietary strategy in the parionins with the others. As mentioned before, primigenium hipparionins from the central Euro- western Mediterranean H. concudense and H. cf. 17 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR matthewi most likely fed on grasses, while the intermediate feeding preferences in the macedoni- other hipparionins were probably mixed-feeders cum hipparionins, in contrast to previously reported including then more browse in their diets. The Tur- grazing diets (Hayek et al., 1992; Koufos et al., olian primigenium group from the western Mediter- 2006; Solounias et al., 2010). Merceron et al. ranean could also have followed a somewhat (2016a) also detected lower grass consumption grazing strategy. However, the small sample hin- preferences compared to obligate grazers (variable ders a more reliable interpretation. Further compar- grazing) and even mixed-feeding within the dietri- isons are not possible since no other dental wear chi and macedonicum groups; a pattern that they studies on Turolian western Mediterranean hippari- related to the inclusion of more browse during dry onins have hitherto been done. The smaller hippar- seasons. This last interpretation can be supported ionins from this region, on the other hand, were by our results pointing to intermediate feeding pref- generalist mixed-feeders that fed on a higher per- erences but with narrow daily/weekly dietary spec- centage of browse than other western hipparionins. tra. In the eastern Mediterranean, and especially in the Local populations within each hipparionin Balkans bioprovince, the hipparionins show again group also show some differences in their more complex microwear textures, which we have microwear textures. For example, the macedoni- mainly related to the higher consumption of browse cum and dietrichi hipparionins from Nikiti-2 grazed during seasonal dry phases when the herbaceous more than their analogues from Perivolaki. To a layer is poor (see previous section). In this regard, lesser extent, the macedonicum hipparionins from the Balkans’ macedonicum group included in their Nikiti-2 consumed higher proportion of grasses diet—besides grasses—more quantity of hard than those from the localities of Ravin des Zou- browse material in comparison to other western aves-5 and Dytiko. Additionally, broader dietary Mediterranean and western Anatolian hipparionins. preferences have been detected in the macedoni- This group, however, fed likely on a narrow range cum group from Gülpınar, and in the proboscideum of items on a daily basis (as suggested by the low and primigenium hipparionins from Hadjidimovo in HAsfc values), thus pointing to a seasonal mixed- comparison to their counterparts from other sites. feeding strategy rather than a “meal-by-meal” one Comparable dietary variations within the same hip- (Solounias and Semprebon, 2002). parionin group present in different localities have Previous dietary reconstructions of eastern already been identified (Kaiser, 2003). These dif- Mediterranean Turolian hipparionins have mainly ferences illustrate the influence of the local envi- inferred grazing diets (Hayek et al., 1992; Koufos ronments; like the possible presence of a richer et al., 2009; Solounias et al., 2010). Our results herbaceous layer including monocots in Nikiti-2, as rather point to more intermediate feeding prefer- well as a more diverse habitat structure or higher ences both in a daily or seasonal basis. Similar intra- or inter-specific competition levels in mixed-feeding diets have also been suggested Gülpınar and Hadjidimovo sites. within the proboscideum group (Hayek et al., 1992; In agreement with this pattern, we find a quite Solounias et al., 2010), while other authors indi- homogeneous dental microwear texture within cated a more grazing tendency for this group (Kou- each fossil site, with no significant differences fos et al., 2009; Clavel et al., 2012). In our sample, between hipparionin groups coexisting on the although being mixed-feeders, the proboscideum same locality. We therefore suggest that the taxa hipparionins from the western Anatolia represent present in one area exploited similar resources. the forms that grazed more of the eastern Mediter- This does not mean there was no niche partitioning ranean. On the contrary, the Balkan proboscideum between species, but other factors than strictly diet group depicts a “meal-by-meal” generalist feeding may have contributed. The same low degree of behavior (sensu Solounias and Semprebon, 2002) dietary differentiation has also been found in previ- as shown by their higher HAsfc values. The dietri- ous studies on hipparionin diets (Koufos et al., chi and macedonicum hipparionins, on the other 2006; Solounias et al., 2010; Clavel et al., 2012), in hand, do not differ in diet between the two eastern other extinct perissodactyls (Mihlbachler and bioprovinces. In the case of the dietrichi group, our Solounias, 2002), and even in extant ungulate inferred mixed-feeding strategy agrees with previ- assemblages (De Iongh et al., 2011). The pres- ous interpretations based on material from Samos ence of various hipparionin groups with no clear (Koufos et al., 2009), but contrasts with those that trophic niche differentiation can therefore be suggest a clear grazing diet (Hayek et al., 1992; explained by: 1) the wide mixed-feeding strategies Solounias et al., 2010). Our results also point to that allow them to consume a large variety of 18 PALAEO-ELECTRONICA.ORG resources (diminishing the trophic competition), 2) increased tooth height appeared once within the the body size differences that might favor the clade as an adaptation to more abrasive diets, and exploitation of different herbaceous strata (Koufos that this condition was retained despite the follow- et al., 2006) in a diverse and rich environment ing shifts in the dietary strategies. This interpreta- (Solounias et al., 2010), or 3) by differences on tion, however, fails to explain the observed social and migratory behaviour. The coexistence in hypsodonty increase through time in many hippari- Hadjidimovo of two large hipparionins, Hipparion onin groups (Alberdi, 1989). Alternatively, other mediterraneum and Hipparion brachypus (Hris- authors emphasized that hipparionin hypsodont tova, 2009) that show some of the broadest dietary teeth could represent an adaptation to flexible spectra of our sample (higher HAsfc), may support dietary habits (Kaiser, 2003; Tütken et al., 2013). In the hypothesis of an expansion of the dietary pref- agreement with this interpretation, our results show erences due to competition rather than a niche dif- that most of the hypsodont hipparionins had mixed- ferentiation strategy. In our sample, however, we feeding strategies either in a daily or a seasonal have also detected some minor differences that basis. This feeding flexibility might have repre- may suggest a case of niche differentiation within sented an advantageous trait during the climatic El Arquillo fossil site from the western Mediterra- shifts occurred during the late Miocene (Tütken et nean area. Here, the smallest hipparionins follow a al., 2013), since herbivores dealing with instable more browse dominated generalist diet compared resource supplies tend to expand their dietary to the larger primigenium group. breaths (Winkler et al., 2013). Nonetheless, hyp- sodonty has also been related to increasing envi- Hypsodonty and Hipparionin Diets ronment aridity, as indicated by the inverse Surprisingly, the larger and more grazing correlation of the hypsodonty with the rainfall and taxon from El Arquillo has lower-crowned teeth, humidity (Fortelius et al., 2002). In this sense, air- while the smaller and more mixed-feeders periafri- borne grit has been hypothesized to favor higher canum and gromovae hipparionins show the high- crowned teeth [see Strömberg (2006)] due to its est hypsodonty index of the western Mediterranean contribution to dental wear (Sanson et al., 2007; Turolian (Pesquero, 2003). Despite their hypsodont Madden, 2014). Interestingly, however, recent teeth, most of the hipparionin groups analyzed studies have demonstrated that despite different here have shown to be intermediate feeders. The grit loads in the grass consumed by African buffa- same lack of correspondence between the hippari- loes, their dental wear rate does not significantly onin high-crowned teeth and a strict grazing diet differ (Sanson et al., 2017). have been discussed in various studies dealing Whether by means of phytolith or grit wear, with dental wear and isotopes (Hayek et al., 1992; higher-crowned teeth might also contribute to the MacFadden et al., 1999; Solounias et al., 2010; achievement of a longer life span (Carranza et al., Tütken et al., 2013). Similarly, extant ungulates 2004; Veiberg et al., 2007; Jordana et al., 2012), show discrepancies between diet and their dental which is linked to a generally slower life history morphology, as shown by the red deer ingesting (Stearns, 1992). Indeed, as well as by the diet large quantity of monocots (Azorit et al., 2012; Ber- quality, the wear degree has shown to be influ- lioz et al., 2017) despite their mesodont teeth, or enced by the optimal timing of tooth use in relation the hypsodont teeth of the mouflon considering to the schedule of growth and reproduction through their mixed feeding preferences (Marchand et al., life (Pérez-Barbería et al., 2015). More hypsodont 2013; Merceron et al., 2021). teeth, then, can be related to a higher resource When testing the general correspondence assignation to the soma maintenance rather than between grazing diets and hypsodonty within Equi- to current reproductive performance, a life history dae representatives, both Strömberg (2006) and strategy which is in turn coupled to longer repro- Mihlbachler et al. (2011) identified large periods of ductive lifespans (Veiberg et al., 2007; Carranza et time when the selective pressures leading to al., 2008). Enamel folding complexity on the occlu- higher crowned teeth (e.g., dietary abrasives) were sal surface, moreover, might have also played an weak. However, the same authors found that important role in the efficiency of the hipparionin during specific intervals there were strong selective tooth durability (Famoso and Davis, 2016); while in pressures leading to a rapid change on equids’ the Equus genus dental functionality is chiefly dentition (Strömberg, 2006; Mihlbachler et al., maintained by means of increased crown heights 2011). In the case of hipparionin horses, MacFad- due to the extension of the crown formation time den et al. (1999) initially proposed that the (Nacarino-Meneses et al., 2017; Orlandi-Oliveras 19 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR et al., 2019). The relationship between life history smaller form, hence, probably dwelt in more het- and dental development (Smith, 1991, 2000), erogeneous habitats as already proposed by For- together with the inferred slow molar formation and sten (1997). The sharpest dietary dissimilarities relatively late eruption of hipparionins’ molars between size groups, however, are found in the (Orlandi-Oliveras et al., 2019), make us interpret western Mediterranean Turolian. Nowadays, the the lack of linkage between hypsodonty and diet in large size of extant grazing plain zebras allows hipparionins as possible evidence of the role of life them to go through the seasonal migrations follow- history in the evolution of tooth hypsodonty within ing the grasses fluxes (Moehlman, 2002). In the this group. western Mediterranean, likewise, larger-sized hip- parionins were the taxa with the stronger grazing Size Decrease Trends tendencies, and they might arguably undergo sea- The decrease in hipparionin size has mainly sonal migrations when the resources in monocoty- been related to an adaptation to open landscapes ledonous were depleted. The smaller and more (Bernor et al., 1996; Forsten, 1997; Saarinen, hypsodont species, on the other hand, followed 2009) and to feeding on plants of increasing xero- browse-dominated mixed-feeding strategies; prob- phytism (Forsten, 1968, 1978b). Accordingly, ably exploiting the available resources in some- Saarinen et al. (2021) demonstrated that this rela- what closer habitats, and broadening the spectrum tionship holds true in the Pleistocene Equus of of ingested items during seasons of lower resource Europe, as large-sized forms were more associ- availability. Accordingly, bone and dental paleohis- ated to forested habitats while the smaller Equus to tological studies have pointed towards relative opener ones. In the case of hipparionins, on the slower-life histories in these more hypsodont small- other hand, Ortiz-Jaureguizar and Alberdi (2003) sized forms in comparison to larger hipparionins suggested more closed-habitat affinities for the from the western Mediterranean Turolian (Orlandi- small forms, while in a recent review Bernor et al. Oliveras et al., 2018, 2019). Similarly, extant roe (2021) related the smaller taxa to grazing open deer populations of less productive environments habitat dwellers. are smaller, more hypsodont, and more longer- If the hipparionin small size (that is, the trend lived than larger-sized roe deer populations inhab- towards smaller size) was the consequence of iting highly productive environments (Veiberg et al., direct adaptation to specific diets or habitats (i.e., 2007). the spread of opener habitats and/or xerophytic flora), we would expect shared dietary regimes and CONCLUSIONS habitat preferences among small-sized forms. The dental microwear textures of the northern Here, however, we do not find a common dietary circum-Mediterranean hipparionins mainly point pattern shared between the small-sized hipparion- towards mixed-feeding strategies. Some excep- ins of Vallesian and Turolian assemblages from the tions are present, since large-sized forms of the circum-Mediterranean regions. In consequence, Turolian western Mediterranean grazed more than we interpret that the size differences were not the rest. When considering all the hipparionins directly promoted by a common dietary or habitat analyzed, we do not find a common relationship shift but might instead represent independent between their dietary preferences and their size. adaptations that otherwise led to similar size However, despite this lack of general correlation, decrease tendencies. the western Mediterranean large-sized forms Indeed, the small- and large-sized groups tended to have narrower dietary breadths further from the eastern Mediterranean did not follow con- associated to a higher percentage of grassy con- trasting dietary regimes during the Vallesian and sumption in comparison to smaller hipparionins. the Turolian. This suggests that the cause or On the other hand, the different-sized hipparionins causes triggering the small-sized hipparionin from the eastern bioprovinces followed similar appearance were not directly related to dietary dif- intermediate feeding strategies, including both ferences. Otherwise, it lends support to the idea browse and grasses in their diets (in some cases in that shifts in other factors probably underlay these a more seasonal basis and others in a more daily- changes [e.g., mortality regimes shift (Orlandi-Oli- weekly basis). Although we did not reconstruct the veras et al., 2018)]. During the Vallesian, the main paleoenvironmental conditions from the sole diet of dietary difference detected in the western Mediter- hipparionins, their opportunistic feeding adapta- ranean hipparionins resides in the more generalist tions give us clues about the habitats in which they diets followed by the smaller hipparionins. The might have dwelt. Therefore, due to the differential 20 PALAEO-ELECTRONICA.ORG dietary regimes among the small-sized forms ana- might have been influenced by its role on dietary lyzed, our results question the idea that hipparionin flexibility (Tütken et al., 2013) and life history size decrease was a direct adaptation to habitat (Veiberg et al., 2007), although the presence of grit openness. due to habitat openness can also be involved. The broad comparison between Vallesian and Finally, the different ecologies shown by the small- Turolian hipparionin assemblages from different sized hipparionins make us conclude that the size areas also allowed us to detect some general spa- decrease trends were probably achieved inde- tiotemporal differences regarding the hipparionin pendently rather than related to a common habitat feeding strategies. The inclusion of tough items in shift. their diets tended to increase from Vallesian to Tur- olian; in the eastern Mediterranean, a further wid- ACKNOWLEDGEMENTS ening of the dietary strategies is also detected. We would like to thank M. Fernández and X. This could reflect a general increase in plant xero- Aymerich for the molding of the material from the phytism, and the presence of more heterogeneous ICP (Institut Català de Paleontologia Miquel Crusa- environments in the eastern Mediterranean late font). G.O-O. acknowledges the help received from Miocene. More solid paleoenvironmental infer- F. Martin (PALEVOPRIM) during the obtainment of ences, however, should be based on dietary recon- the DMT parameters and the posterior analyses. structions of more diverse ungulate assemblages We further thank to D. Kostopoulos (Aristotle Uni- (adding other dietary proxies as isotopes and versity of Thessaloniki) for his comments on the mesowear) and the study of macrobotanical and earlier versions of this manuscript. The editors (Y. palynological remains. When comparing the east- Nakamura, A. Bush, and J.X. Samuels) and four ern and western Mediterranean regions, we find reviewers including J. Saarinen are acknowledged significant higher complexity values in the eastern for their helpful comments. Moreover, we would like forms, specifically on the Balkans. One possible to thank to the authorities of the following museum interpretation to this observation is the presence of collections to give access to the related materials: higher levels of millimetric grit eastwards (probably Museo Nacional de Ciencias Naturales (MNCN), linked to a more arid environment). However, con- ICP museum, Laboratory of Geology and Palaeon- sidering previous studies comparing both areas tology at the University of Thessaloniki, Palaeonto- (Bonis et al., 1992; Koufos, 2006), we also relate logical Museum Dimitar Kovachev at Asenovgrad, this to the presence of more dry seasonal episodes and the Ege University Natural History Museum. (Merceron et al., 2005a, 2016a) inducing the con- Funding for this study was provided by the Grant sumption of harder woody browse by eastern hip- PID2020-117118GBI00 funded by MCIN/AEI/ parionins. Similarly, extant equids (Estes, 1991; 10.3039/501100011033 (M.K), the project Moehlman, 2002) and other ungulates (De Iongh et CGL2015-63777 (M.K), and the CERCA Program, al., 2011) include higher proportion of browse Generalitat de Catalunya. R.S.S., T.K., S.M., and during the dry seasons in savanna and more arid G.M. were granted through a “Wenner-Gren Inter- environments. national Collaborative Research Grant” (PIs: R.S. In some cases, the diet of the hipparionin Scott and T. Kaya) to collect most of the Vallesian groups differs between the fossil sites surveyed, and Turolian equid dental molds from the eastern probably reflecting the season at which most of the Mediterranean, and S.M. and T.K. were supported specimens died and the influence of local condi- by the Ege University Research Projects TTM/001/ tions. Accordingly, coexisting hipparionins show no 2015 and TTM/001/2016. M.K. and G.O-O. were differences on the dental microwear patterns, thus part of a research group recognized without fund- suggesting no strong dietary niche partitioning over ing by AGAUR (2017 SGR 960) and G.O-O. was the traditional grazing-browsing couple. Alterna- supported by a FI-DGR 2016 grant tively, the segregation might have existed among (2016FI_B00202) awarded by AGAUR (Generalitat the frame of mixed-feeders and browsers (exploit- de Catalunya) and held an Erasmus + fellowship ing different resources but with similar mechanical during his stay in the PALEVOPRIM laboratory properties). The general mixed-feeding strategy (CNRS and University of Poitiers). The grant SYN- inferred in most of the hypsodont hipparionin THESIS ES-TAF-1846 for the stay of J.C. at the groups shows no support to the assumption of MNCN of Madrid is also acknowledged. grazing diets due to high hypsodonty indices. This supports, hence, that hypsodonty within the group 21 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR REFERENCES Ackermans, N.L., Martin, L.F., Codron, D., Hummel, J., Kircher, P.R., Richter, H., Kaiser, T.M., Clauss, M., and Hatt J.M. 2020a. Mesowear represents a lifetime signal in sheep (Ovis aries) within a long-term feeding experiment. Palaeogeography, Palaeoclimatology, Palaeoecology, 553:109793. https://doi.org/10.1016/j.palaeo.2020.109793 Ackermans, N.L., Winkler, D.E., Martin, L.F., Kaiser, T.M., Clauss, M., and Hatt, J.M. 2020b. Dust and grit matter: Abrasives of different size lead to opposing dental microwear textures in experimentally fed sheep (Ovis aries). Journal of Experimental Biology, 223:jeb220442. https://doi.org/10.1242/jeb.220442 Adams, N.F., Gray, T., and Purnell, M.A. 2020. Dietary signals in dental microwear of predatory small mammals appear unaffected by extremes in environmental abrasive load. Palaeogeography, Palaeoclimatology, Palaeoecology, 558:109929. | https://doi.org/10.1016/j.palaeo.2020.109929 Agustı,́ J., Sanz de Siria, A., and Garcés, M. 2003. Explaining the end of the hominoid experiment in Europe. Journal of Human Evolution, 45:145-153. https://doi.org/10.1016/S0047-2484(03)00091-5 Alberdi, M.T. 1989. A review of Old World hipparionine horses, p. 234-261. In Prothero, D.R. and Schoch, R.M. (eds.), The Evolution of Perissodactyls. Oxford University Press, New York. Alberdi, M.T., Prado, J.L., and Ortiz-Jaureguizar, E. 1995. Patterns of body size changes in fossil and living Equini (Perissodactyla). Biological Journal of the Linnean Society, 54:349-370. https://doi.org/10.1111/j.1095-8312.1995.tb01042.x Azorit, C., Tellado, S., Oya, A., and Moro, J. 2012. Seasonal and specific diet variations in sympatric red and fallow deer of southern Spain: a preliminary approach to feeding behaviour. Animal Production Science, 52:720-727. https://doi.org/10.1071/AN12016 Bauer, I.E., McMorrow J., and Yalden, D.W. 1994. The historic ranges of three equid species in north-east Africa: a quantitative comparison of environmental tolerances. Journal of Biogeography, 21:169-182. https://doi.org/10.2307/2845470 Bell, R.H.V. 1971. A grazing ecosystem in the Serengeti. Scientific American, 225:86-93. Berlioz, E., Azorit, C., Blondel, C., Ruiz, M.S.T., and Merceron, G. 2017. Deer in an arid habitat: dental microwear textures track feeding adaptability. Hystrix the Italian Journal of Mammalogy, 28:222-230. https://doi.org/10.4404/hystrix-28.2-12048 Bernor, R.L. and Tobien, H. 1989. Two small species of Cremohipparion (Equidae, Mamm.) from Samos, Greece. Mitteilungen der Bayerischen Staatssammlung für Paläontologie und Historische Geologie, 29:207-226. Bernor, R.L., Kovar-Eder, J., Suc, J.-P., and Tobien, H. 1990a. A contribution to the evolutionary history of European Late Miocene age hipparionines (Mammalia: Equidae). Paléobiologie Continentale, 17:291-309. Bernor, R.L., Tobien, H., and Woodburne, M.O. 1990b. Patterns of Old World hipparionine evolutionary diversification and biogeographic extension, p. 263-319. In Lindsay, E.H., Fahlbusch, V., and Mein, P. (eds.), European Neogene Mammal Chronology. Plenum Press, New York. https://doi.org/10.1007/978-1-4899-2513-8_18 Bernor, R.L., Koufos, G.D., Woodburne, M.O., and Fortelius, M. 1996. The evolutionary history and biochronology of European and Southwest Asian Late Miocene and Pliocene hipparionine horses, p. 307-338. In Bernor, R.L., Fahlbusch, V., and Mittmann, H.-W. (eds.), The Evolution of Western Eurasian Neogene Mammal Faunas. Columbia University Press, New York. Bernor, R.L., Scott, R.S., Fortelius, M., Kappelman J., and Sen, S. 2003. Equidae (Perissodactyla), p. 220-281. In Fortelius, M., Kappelman, J., Sen, S., and Bernor, R.L. (eds.), The Geology and Paleontology of the Miocene Sinap Formation, Turkey. Columbia University Press. Bernor, R.L., Mirzaie Ataabadi, M., Meshida, K., and Wolf, D. 2016. The Maragheh hipparions, late Miocene of Azarbaijan, Iran. Palaeobiodiversity and Palaeoenvironments, 96:453-488. https://doi.org/10.1007/s12549-016-0235-2 Bernor, R.L., Kaya, F., Kaakinen, A., Saarinen, J., and Fortelius, M. 2021. Old world hipparion evolution, biogeography, climatology and ecology. Earth-Science Reviews, 221:103784. https://doi.org/10.1016/j.earscirev.2021.103784 22 PALAEO-ELECTRONICA.ORG Böhme, M., Ilg, A., and Winklhofer, M. 2008. Late Miocene “washhouse” climate in Europe. Earth and Planetary Science Letters, 275:39401. https://doi.org/10.1016/j.epsl.2008.09.011 Böhme, M., Winkelhofer, M., and Ilg, A. 2011. Miocene precipitation in Europe – temporal trends and spatial gradients. Palaeogeography, Palaeoclimatology, Palaeoecology, 304:212-218. https://doi.org/10.1016/j.palaeo.2010.09.028 Brown, J.S. 1988. Patch use as an indicator of habitat preference, predation risk, and competition. Behavioral Ecology and Sociobiology, 22:37-47. https://doi.org/10.1007/BF00395696 Burgman, J.H.E., Leichliter, J., Avenant, N.L., and Ungar, P.S. 2016. Dental microwear of sympatric rodent species sampled across habitats in southern Africa: Implications for environmental influence. Integrative Zoology, 11:111-127. https://doi.org/10.1111/1749-4877.12188 Calandra, I. and Merceron, G. 2016. Dental microwear texture analysis in mammalian ecology. Mammal Review, 46:215-218. https://doi.org/10.1111/mam.12063 Calder, W.A. 1984. Size, Function, and Life History. Harvard University Press, Cambridge. Cantalapiedra, J.L., Prado, J.L., Hernández Fernández, M., and Alberdi, M.T. 2017. Decoupled ecomorphological evolution and diversification in Neogene-Quaternary horses. Science, 355:627-630. https://doi.org/10.1126/science.aag1772 Carranza, J., Alarcos, S., Sánchez-Prieto, C.B., Valencia, J., and Mateos, C. 2004. Disposable- soma senescence mediated by sexual selection in an ungulate. Nature, 432:215-218. https://doi.org/10.1038/nature03004 Carranza, J., Mateos, C., Alarcos, S., Sánchez-Prieto, C.B., and Valencia, J. 2008. Sex-specific strategies of dentine depletion in red deer. Biological Journal of the Linnean Society, 93:487- 497. https://doi.org/10.1111/j.1095-8312.2007.00903.x Case, T.J. 1979. Optimal body size and an animal’s diet. Acta Biotheoretica, 28: 54-69. https://doi.org/10.1007/BF00054680 Clavel, J., Merceron, G., Hristova, L., Spassov, N., Kovachev, D., and Escarguel, G. 2012. On Mesopithecus habitat: Insights from late Miocene fossil vertebrate localities of Bulgaria. Journal of Human Evolution, 63:162-179. https://doi.org/10.1016/j.jhevol.2012.04.007 Codron, D., Lee-Thorp, J.A., Sponheimer, M., Codron, J., De Ruiter, D., and Brink, J.S. 2007. Significance of diet type and diet quality for ecological diversity of African ungulates. Journal of Animal Ecology, 76:526-537. https://doi.org/10.1111/j.1365-2656.2007.01222.x Conover, W.J. and Iman, R.L. 1981. Rank transformations as a bridge between parametric and nonparametric statistics. The American Statistician, 35:124-129. https://doi.org/10.2307/2683975 Damuth, J.D. and MacFadden, B.J. 1990. Body Size in Mammalian Paleobiology: Estimation and Biological Implications. Cambridge University Press, Cambridge. Davis, M. and Pineda?Munoz, S. 2016. The temporal scale of diet and dietary proxies. Ecology and evolution, 6:1883-1897. https://doi.org/10.1002/ece3.2054 de Bonis, L., Bouvrain, G., Geraads, D., and Koufos, G.D. 1992. Diversity and paleoecology of Greek late Miocene mammalian faunas. Palaeogeography, Palaeoclimatology, Palaeoecology, 91:99-121. https://doi.org/10.1016/0031-0182(92)90035-4 De Iongh, H.H., De Jong, C.B., Van Goethem, J., Klop, E., Brunsting, A.M.H., Loth, P.E., and Prins, H.H.T. 2011. Resource partitioning among African savanna herbivores in North Cameroon: The importance of diet composition, food quality and body mass. Journal of Tropical Ecology, 27:503-513. https://doi.org/10.1017/S0266467411000307 Denk, T. 2016. Palaeoecological interpretation of the late Miocene landscapes and vegetation of northern Greece: A comment to Merceron et al., 2016 (Geobios 49, 135–146). Geobios, 49:423-431. https://doi.org/10.1016/j.geobios.2016.06.009 Denk, T., Zohner, C.M., Grimm, G.W., and Renner, S.S. 2018. Plant fossils reveal major biomes occupied by the late Miocene Old-World Pikermian fauna. Nature Ecology and Evolution, 2:1864-1870. https://doi.org/10.1038/s41559-018-0695-z DeSantis, L.R.G. 2016. Dental microwear textures: Reconstructing diets of fossil mammals. Surface Topography: Metrology and Properties, 4:023002. DeSantis, L.R.G., Scott, J.R., Schubert, B.W., Donohue, S.L., McCray, B.M., Van Stolk, C.A., Winburn, A.A., Greshko, M.A., and O’Hara, M.C. 2013. Direct comparisons of 2D and 3D dental microwear proxies in extant herbivorous and carnivorous mammals. PLoS ONE, 8:e71428. https://doi.org/10.1371/journal.pone.0071428 23 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR Dmitriew, C.M. 2011. The evolution of growth trajectories: what limits growth rate? Biological Reviews, 86:97-116. https://doi.org/10.1111/j.1469-185X.2010.00136.x Donzelli, D., De Michele, C., and Scholes, R.J. 2013. Competition between trees and grasses for both soil water and mineral nitrogen in dry savannas. Journal of Theoretical Biology, 332:181-190. https://doi.org/10.1016/j.jtbi.2013.04.003 Eisenmann, V. and Sondaar, P.Y. 1998. Pliocene vertebrate locality of Çalta, Ankara, Turkey. 7. Hipparion. Geodiversitas, 20:409-439. Estes, R. 1991. The Behavior Guide to African Mammals: Including Hoofed Mammals, Carnivores, Primates. University of California Press, Berkeley. Famoso, N.A. and Davis, E.B. 2016. On the relationship between enamel band complexity and occlusal surface area in Equids (Mammalia, Perissodactyla). PeerJ, 4:e2181. https://doi.org/10.7717/peerj.2181 February, E.C., Higgins, S.I., Bond, W.J., and Swemmer, L. 2013. Influence of competition and rainfall manipulation on the growth responses of savanna trees and grasses. Ecology, 94:1155-1164. https://doi.org/10.1890/12-0540.1 Forsten, A. 1968. Revision of the palearctic Hipparion. Acta Zoologica Fennica, 119:1-134. Forsten, A. 1978a. Hipparion primigenium (v. Meyer, 1829), an early three-toed horse. Annales Zoologici Fennici, 15:298-313. Forsten, A. 1978b. Hipparion and possible Iberian-North African Neogene connections. Annales Zoologici Fennici, 15:294-297. Forsten, A. 1997. Hipparion from Santiga (Spain) and its biostratigraphic significance. Paleontologia i Evolució, 30-31:77-82. Forsten, A. and Kaya, T. 1995. The hipparions (Mammalia, Equidae) from Gülpinar (Canakkale, Turkey). Paläontologische Zeitschrift, 69:491-501. https://doi.org/10.1007/BF02987809 Fortelius, M., Werdelin, L., Andrews, P., Bernor, R.L., Gentry, A., Humphrey, L., Mittmann, H.W., and Viranta, S. 1996. Provinciality, diversity, turnover and paleoecology in land mammal faunas of the later Miocene of Western Eurasia, p. 414-448. In Bernor, R.L., Fahlbusch, V., and Mittmann, H.-W. The Evolution of Western Eurasian Neogene Mammal Faunas. Columbia University Press. Fortelius, M., Eronen, J.T., Jernvall, J., Liu, L., Pushkina, D., Rinne, J., Tesakov, A., Vislobokova, I.A., Zhang, Z., and Zhou, L. 2002. Fossil mammals resolve regional patterns of Eurasian climate change during 20 million years. Evolutionary Ecology Research, 4:1005-1016. Gabunia, L.K. and Chochieva, K.I. 1982. Co-evolution of the Hipparion fauna and vegetation in the Paratethys region. Evolutionary Theory, 6:1-13. Gagnon, M. and Chew, A.E. 2000. Dietary preferences in extant African Bovidae. Journal of Mammalogy, 81:490-511. https://doi.org/10.1644/1545-1542(2000)081<0490:DPIEAB>2.0.CO;2 Gould, G.C. and MacFadden, B.J. 2004. Gigantism, dwarfism, and Cope’s Rule: “nothing in evolution makes sense without a phylogeny”. Bulletin of the American Museum of Natural History, 285:219-237. https://doi.org/10.1206/0003-0090(2004)285<0219:C>2.0.CO;2 Hayek, L.-A.C., Bernor, R.L., Solounias, N., and Steigerwald, P. 1992. Preliminary studies of hipparionine horse diet as measured by tooth microwear. Annales Zoologici Fennici, 28:187- 200. Hedberg, C. and DeSantis, L.R.G. 2017. Dental microwear texture analysis of extant koalas: clarifying causal agents of microwear. Journal of Zoology, 301:206-214. https://doi.org/10.1111/jzo.12413 Hilgen, F.J., Lourens, L.J., van Dam, J., Beu, A.G., Boyes, A.F., Cooper, R.A., Krijgsman, W., Ogg, J.G., Piller, W.E., and Wilson, D.S. 2012. The Neogene Period, p. 923-978. In Gradstein, F.M., Ogg, J.G., Schmitz, M., and Ogg, G. (eds.), The Geologic Time Scale 2012. https://doi.org/10.1016/B978-0-444-59425-9.00029-9 Hipondoka, M.H., Aranibar, J., Chirara, C., Lihavha, M., and Macko, S. 2003. Vertical distribution of grass and tree roots in arid ecosystems of Southern Africa: niche differentiation or competition? Journal of Arid Environments, 54:319-325. https://doi.org/10.1006/JARE.2002.1093 Hopcraft, J.G.C., Olff, H., and Sinclair, A.R.E. 2010. Herbivores, resources and risks: alternating regulation along primary environmental gradients in savannas. Trends in Ecology and Evolution, 25:119-128. https://doi.org/10.1016/j.tree.2009.08.001 Hua, L., Chen, J., and Ungar, P.S. 2020. Diet reduces the effect of exogenous grit on tooth microwear. Biosurface and Biotribology, 3:48-52. https://doi.org/10.1049/bsbt.2019.0041 24 PALAEO-ELECTRONICA.ORG Hullot, M., Antoine, P.O., Ballatore, M., and Merceron, G. 2019. Dental microwear textures and dietary preferences of extant rhinoceroses (Perissodactyla, Mammalia). Mammal Research, 64:397-409. https://doi.org/10.1007/s13364-019-00427-4 Hristova, L. 2009. Ontogeny and variability in the cheek region of hipparions from the late Miocene locality of Hadzhidimovo-1, southwest Bulgaria. Rivista Italiana di Paleontologia e Stratigrafia, 115:125-132. https://doi.org/10.13130/2039-4942/5924 Ioakim, C. and Koufos, G.D. 2009. Palynology, p. 27-35. In Koufos, G.D. and Nage, D. (eds.), The late Miocene Mammal Faunas of the Mytilinii Basin, Samos Island, Greece: New Collection. Beiträge zur Paläontologie, 31. Janis, C.M. 2008. An evolutionary history of browsing and grazing ungulates, p. 21-45. In Gordon, I.J. and Prins, H.H.T. (eds.), The Ecology of Browsing and Grazing. Ecological Studies. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-72422-3_2 Jarman, P.J. 1974. The social organisation of antelope in relation to their ecology. Behaviour, 48:215-267. https://www.jstor.org/stable/4533573 Jiménez-Moreno, G., Popescu, S.M., Ivanov, D., and Suc, J.-P. 2007. Neogene flora, vegetation and climate dynamics in southeastern Europe and the northeastern Mediterranean, p. 503- 516. In Willians, W., Haywood, A.M., Gregory, F.J., and Schmidt, D.N. (eds.), Deep-Time Perspectives on Climate Change: Marrying the Signal from Computer Models and Biological Proxies. The Micropalaeontological Society, London. Jordana, X., Marín-Moratalla, N., DeMiguel, D., Kaiser, T.M., and Köhler, M. 2012. Evidence of correlated evolution of hypsodonty and exceptional longevity in endemic insular mammals. Proceedings of the Royal Society B: Biological Sciences, 279:3339-3346. https://doi.org/10.1098/rspb.2012.0689 Kaiser, T.M. 2003. The dietary regimes of two contemporaneous populations of Hippotherium primigenium (Perissodactyla, Equidae) from the Vallesian (Upper Miocene) of Southern Germany. Palaeogeography, Palaeoclimatology, Palaeoecology, 198:381-402. https://doi.org/10.1016/S0031-0182(03)00480-2 Kostopoulos, D.S. 2009. The Pikermian Event: Temporal and spatial resolution of the Turolian large mammal fauna in SE Europe. Palaeogeography, Palaeoclimatology, Palaeoecology, 274:82-95. https://doi.org/10.1016/j.palaeo.2008.12.020 Koufos, G.D. 1990. The hipparions of the lower Axios Valley (Macedonia, Greece) Implications for the Neogene stratigraphy and the evolution of hipparions, p. 321-338. In Lindsay, E.H., Fahlbusch, V., and Mein, P. (eds.), European Neogene Mammal Chronology. Plenum Press, New York. https://doi.org/10.1007/978-1-4899-2513-8_19 Koufos, G.D. 2006. Palaeoecology and chronology of the Vallesian (late Miocene) in the Eastern Mediterranean region. Palaeogeography, Palaeoclimatology, Palaeoecology, 234:127-145. https://doi.org/10.1016/j.palaeo.2005.01.014 Koufos, G.D. 2016. Hipparion macedonicum revisited: New data on evolution of hipparionine horses from the Late Miocene of Greece. Acta Palaeontologica Polonica, 61:519-536. https://doi.org/10.4202/app.00169.2015 Koufos, G.D., Merceron, G., Kostopoulos, D.S., Vlachou T.D., and Sylvestrou, I.A. 2006. Palaeoecology and Palaeobiogeography, p. 201-221. In Koufos, G.D. (ed.), The late Miocene Vertebrate Locality of Perivolaki, Thessaly, Greece. Palaeontographica Abteilung A, 276. Koufos, G.D., Kostopoulos, D.S., and Merceron, G. 2009. Palaeoecology – Palaeobiogeography, p. 409-430. In Koufos, G.D. and Nagel, D. (eds.), The late Miocene Mammal Faunas of the Mytilinii Basin, Samos Island, Greece: new collection. Beiträge zur Paläontologie, 31. Koufos, G.D. and Vlachou, T.D. 2016. Equidae, p. 85-118. In Koufos, G.D. and Kostopoulos, D.S. (eds.), Palaeontology of the Upper Miocene Vertebrate Localities of Nikiti (Chalkidiki Peninsula, Macedonia, Greece). Geobios, 49. https://doi.org/10.1016/j.geobios.2016.01.001 Langsrud, Ø. 2003. ANOVA for unbalanced data: Use Type II instead of Type III sums of squares. Statistics and Computing, 13:163-167. https://doi.org/10.1023/A:1023260610025 Lucas, P.W., Casteren, A. van, Al-Fadhalah, K., Almusallam, A.S., Henry, A.G., Michael, S., Watzke, J., Reed, D.A., Diekwisch, T.G.H., Strait, D.S., and Atkins, A.G. 2014. The role of dust, grit and phytoliths in tooth wear. Annales Zoologici Fennici, 51:143-152. https://doi.org/10.5735/086.051.0215 MacFadden, B.J. 1992. Fossil Horses: Systematics, Paleobiology, and Evolution of the Family Equidae. Cambridge University Press, New York. MacFadden, B.J. 2005. Fossil horses--evidence for evolution. Science, 307:1728-730. https://doi.org/10.1126/science.1105458 25 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR MacFadden, B.J. and Hulbert, R.C. 1988. Explosive speciation at the base of the adaptive radiation of Miocene grazing horses. Nature, 336:466-468. https://doi.org/10.1038/336466a0 MacFadden, B.J., Solounias, N., and Cerling, T.E. 1999. Ancient diets, ecology, and extinction of 5-million-year-old horses from Florida. Science, 283:824-827. https://doi.org/10.1126/science.283.5403.824 Madden, R.H. 2014. Hypsodonty in Mammals: Evolution, Geomorphology and the Role of Earth Surface Processes, Hypsodonty in Mammals: Evolution, Geomorphology and the Role of Earth Surface Processes. Cambridge University Press, Cambridge. Marchand, P., Redjadj, C., Garel, M., Cugnasse, J.M., Maillard, D., and Loison, A. 2013. Are mouflon Ovis gmelini musimon really grazers? A review of variation in diet composition. Mammal Review, 43: 275-291. https://doi.org/10.1111/mam.12000 Martin, F., Plastiras, C.-A., Merceron, G., Souron, A., and Boisserie, J.-R. 2018. Dietary niches of terrestrial cercopithecines from the Plio-Pleistocene Shungura Formation, Ethiopia: evidence from Dental Microwear Texture Analysis. Scientific Reports, 8:14052. https://doi.org/10.1038/s41598-018-32092-z Matthew, W.D. 1926. The evolution of the horse: a record and its interpretation. The Quaterly Review of Biology, 1:139-185. https://www.jstor.org/stable/2808222 Merceron, G., Bonis, L. de, Viriot, L., and Blondel, C. 2005a. Dental microwear of fossil bovids from northern Greece: Paleoenvironmental conditions in the eastern Mediterranean during the Messinian. Palaeogeography, Palaeoclimatology, Palaeoecology, 217:173-185. https://doi.org/10.1016/j.palaeo.2004.11.019 Merceron, G., Bonis, L. de, Viriot, L., and Blondel, C. 2005b. Dental microwear of the late Miocene bovids of northern Greece: Vallesian/Turolian environmental changes and disappearance of Ouranopithecus macedoniensis? Bulletin de la Societe Geologique de France, 176:475-484. https://doi.org/10.2113/176.5.475 Merceron, G., Scott, J.R., Scott, R.S., Geraads, D., Spassov, N., and Ungar, P.S. 2009. Folivory or fruit/seed predation for Mesopithecus, an earliest colobine from the late Miocene of Eurasia? Journal of Human Evolution, 57:732-738. https://doi.org/10.1016/j.jhevol.2009.06.009 Merceron, G., Kaiser, T.M., Kostopoulos, D.S., and Schulz, E. 2010. Ruminant diets and the Miocene extinction of European great apes. Proceedings of the Royal Society B: Biological Sciences, 277:3105-3112. https://doi.org/10.1098/rspb.2010.0523 Merceron, G., Kostopoulos, D.S., Bonis, L. de, Fourel, F., Koufos, G.D., Lécuyer, C., and Martineau, F. 2013. Stable isotope ecology of Miocene bovids from Northern Greece and the ape/monkey turnover in the Balkans. Journal of Human Evolution, 65:185-198. https://doi.org/10.1016/j.jhevol.2013.05.003 Merceron, G., Novello, A., and Scott, R.S. 2016a. Paleoenvironments inferred from phytoliths and Dental Microwear Texture Analyses of meso-herbivores, p. 135-146. In Koufos, G.D. and Kostopoulos, D.S. (eds.), Palaeontology of the upper Miocene vertebrate localities of Nikiti (Chalkidiki Peninsula, Macedonia, Greece). Geobios, 49. https://doi.org/10.1016/j.geobios.2016.01.004 Merceron, G., Ramdarshan, A., Blondel, C., Boisserie, J.-R., Brunetière, N., Francisco, A., Gautier, D., Milhet, X., Novello, A., and Pret, D. 2016b. Untangling the environmental from the dietary: Dust does not matter. Proceedings of the Royal Society B: Biological Sciences, 283:20161032. https://doi.org/10.1098/rspb.2016.1032 Merceron, G., Berlioz, E., Vonhof, H., Green, D., Garel, M., and Tütken, T. 2021. Tooth tales told by dental diet proxies: An alpine community of sympatric ruminants as a model to decipher the ecology of fossil fauna. Palaeogeography, Palaeoclimatology, Palaeoecology, 565:110077. https://doi.org/10.1016/j.palaeo.2020.110077 Mihlbachler, M.C. and Solounias, N. 2002. Body size, dental microwear, and brontothere diets through the Eocene. Journal of Vertebrate Paleontology, 22:88A. Mihlbachler, M.C., Rivals, F., Solounias, N., and Semprebon, G. 2011. Dietary change and evolution of horses in North America. Science, 331:1178-1181. https://doi.org/10.1126/science.1196166 Moehlman, P.D. 2002. Equids: Zebras, Asses, and Horses: Status Survey and Conservation Action Plan. IUCN/SSC Equid Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK. 26 PALAEO-ELECTRONICA.ORG Montoya, P., Morales, J., Robles, F., Abella, J., Benavent, J.V, Marín, M.D., and Ruiz Sánchez, F.J. 2006. Las nuevas excavaciones (1995-2006) en el yacimiento del Mioceno final de Venta del Moro, Valencia. Estudios Geológicos, 62:313-326. Nacarino-Meneses, C., Jordana, X., Orlandi-Oliveras, G., and Köhler, M. 2017. Reconstructing molar growth from enamel histology in extant and extinct Equus. Scientific Reports, 7:15965. https://doi.org/10.1038/s41598-017-16227-2 Nelder, J.A. 1977. A reformulation of linear models. Journal of the Royal Statistical Society. Series A (General), 140:48-77. https://doi.org/10.2307/2344517 Orlandi-Oliveras, G., Nacarino-Meneses, C., Koufos, G.D., and Köhler, M. 2018. Bone histology provides insights into the life history mechanisms underlying dwarfing in hipparionins. Scientific Reports, 8:17203. https://doi.org/10.1038/s41598-018-35347-x Orlandi-Oliveras, G., Nacarino-Meneses, C., and Köhler, M. 2019. Dental histology of late Miocene hipparionins compared with extant Equus, and its implications for Equidae life history. Palaeogeography, Palaeoclimatology, Palaeoecology, 528:133-146. https://doi.org/10.1016/j.palaeo.2019.04.016 Ortiz-Jaureguizar, E. and Alberdi, M.T. 2003. El patrón de cambios en la masa corporal de los Hipparionini (Perissodactyla, Equidae) de la Península Ibérica durante el Mioceno superior- Plioceno superior. Coloquios de Paleontología, 1:499-509. Palkovacs, E.P. 2003. Explaining adaptive shifts in body size on islands: A life history approach. Oikos, 103:37-44. https://doi.org/10.1034/j.1600-0706.2003.12502.x Pérez-Barbería, F.J., Carranza, J., and Sánchez-Prieto, C. 2015. Wear fast, die young: More worn teeth and shorter lives in Iberian compared to Scottish red deer. PLoS One, 10:e0134788. https://doi.org/10.1371/journal.pone.0134788 Pesquero, M.D. 2003. Hipparion del Turoliense superior de Las Casiones (Fosa de Teruel). Coloquios de Paleontología, Volumen Ex:511-548. Pesquero, M.D. and Alberdi, M.T. 2012. New evidence of conspecificity between Hipparion primigenium melendezi Alberdi, 1974 from Los Valles de Fuentidueña (Segovia) and Hipparion concudense concudense Pirlot, 1956 from Concud (Teruel) Spain. Estudios Geológicos, 68:247-260. https://doi.org/10.3989/egeol.40499.152 Pesquero, M.D., Alcalá, L., and Fernández-Jalvo, Y. 2013. Taphonomy of the reference Miocene vertebrate mammal site of Cerro de la Garita, Spain. Lethaia, 46:378-398. https://doi.org/10.1111/let.12016 Peters, R.H. 1983. The Ecological Implications of Body Size. Cambridge Studies in Ecology. Cambridge University Press, Cambridge. https://doi.org/10.1017/CBO9780511608551 Ramdarshan, A., Blondel, C., Gautier, D., Surault, J., and Merceron, G. 2017. Overcoming sampling issues in dental tribology: Insights from an experimentation on sheep. Palaeontologia Electronica 19353:1-19. https://doi.org/10.26879/762 Rey, K., Amiot, R., Lécuyer, C., Koufos, G.D., Martineau, F., Fourel, F., Kostopoulos, D.S., and Merceron, G. 2013. Late Miocene climatic and environmental variations in northern Greece inferred from stable isotope compositions (δ18O, δ13C) of equid teeth apatite. Palaeogeography, Palaeoclimatology, Palaeoecology, 388:48-57. https://doi.org/10.1016/j.palaeo.2013.07.021 Rodgers, W.A. 1982. The decline of large mammal populations on the Lake Rukwa grasslands, Tanzania. African Journal of Ecology, 20:13-22. https://doi.org/10.1111/j.1365-2028.1982.tb01078.x Saarinen, J.J. 2009. Body mass patterns of Eurasian Miocene large land mammals and their connections to environment and climate. Unpublished Master’s Thesis, University of Helsinki, Finland. Saarinen, J.J., Eronen, J., Fortelius, M., Seppä, H., and Lister, A.M. 2016. Patterns of diet and body mass of large ungulates from the Pleistocene of Western Europe, and their relation to vegetation. Palaeontologia Electronica, 19:1-58. https://doi.org/10.26879/443 Saarinen, J.J., Cirilli, O., Strani, F., Meshida, K., and Bernor, R.L. 2021. Testing equid body mass estimate equations on modern zebras–with implications to understanding the relationship of body size, diet, and habitats of Equus in the Pleistocene of Europe. Frontiers in Ecology and Evolution, 9:6222412. https://doi.org/10.3389/fevo.2021.622412 Sanson, G.D., Kerr, S.A., and Gross, K.A. 2007. Do silica phytoliths really wear mammalian teeth? Journal of Archaeological Science, 34:526-531. https://doi.org/10.1016/j.jas.2006.06.009 27 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR Sanson, G.D., Kerr, S.A., and Read, J. 2017. Dietary exogenous and endogenous abrasives and tooth wear in African buffalo. Biosurface and Biotribology, 3:211-223. https://doi.org/10.1016/j.bsbt.2017.12.006 Scheiter, S. and Higgins, S.I. 2007. Partitioning of root and shoot competition and the stability of savannas. American Naturalist, 170:587-601. https://doi.org/10.1086/521317 Schulz-Kornas, E., Winkler, D.E., Clauss, M., Carlsson, J., Ackermans, N.L., Martin, L.F., Hummel, J., Müller, D.W.H., Hatt, J.M., and Kaiser, T.M. 2020. Everything matters: Molar microwear texture in goats (Capra aegagrus hircus) fed diets of different abrasiveness. Palaeogeography, Palaeoclimatology, Palaeoecology, 552:109783. https://doi.org/10.1016/j.palaeo.2020.109783 Scott, J.R. 2012. Dental microwear texture analysis of extant African Bovidae. Mammalia, 76:157-174. https://doi.org/10.1515/mammalia-2011-0083 Scott, K.M. 1990. Postcranial dimensions of ungulates as predictors of body mass, p. 301-335. In Damuth, J. and Macfadden, B.J. (eds.), Body Size in Mammalian Paleobiology: Estimation and Biological Implications. Cambridge University Press, Cambridge. Scott, R.S., Fortelius, M., Huttunen, K., and Armour-Chelu, M. 2003. Abundance of “Hipparion,” p. 380-397. In Fortelius, M., Kappelman, J., Sen, S., and Bernor, R.L. (eds.), The Geology and Paleontology of the Miocene Sinap Formation, Turkey. Columbia University Press. Scott, R.S. and Maga, M. 2005. Paleoecology of the Akkasșdağı hipparions (Mammalia, Equidae), late Miocene of Turkey, p. 809-830. In Sen, S. (ed.), Geology, mammals and environments at Akkasșdağı, late Miocene of Central Anatolia. Geodiversitas, 27. Scott, R.S., Ungar, P.S., Bergstrom, T.S., Brown, C.A., Grine, F.E., Teaford, M.F., and Walker, A. 2005. Dental microwear texture analysis shows within-species diet variability in fossil hominins. Nature, 436:693-695. https://doi.org/10.1038/nature03822 Scott, R.S., Ungar, P.S., Bergstrom, T.S., Brown, C.A., Childs, B.E., Teaford, M.F., and Walker, A. 2006. Dental microwear texture analysis: technical considerations. Journal of Human Evolution, 51:339-349. https://doi.org/10.1016/j.jhevol.2006.04.006 Scott, R.S., Clavel, J., DeMiguel, D., Kaya, T., Kostopoulos, D.S., Mayda, S., and Merceron, G. 2013. Ecology of european hipparionines and the diversity of late Miocene hominids in western Eurasia.14th RCMN Congress Neogene to Quaternary Geological Evolution of Mediterranean, Paratethys and Black Sea. Istanbul, p. 262. Semprebon, G.M., Rivals, F., Solounias, N., and Hulbert, R.C. 2016. Paleodietary reconstruction of fossil horses from the Eocene through Pleistocene of North America Palaeogeography, Palaeoclimatology, Palaeoecology, 442:110-127. https://doi.org/10.1016/j.palaeo.2015.11.004 Smith, B.H. 1991. Dental development and the evolution of life history in Hominidae. American Journal of Physical Anthropology, 86:157-174. https://doi.org/10.1002/ajpa.1330860206 Smith, B.H. 2000. ‘Schultz’s Rule’ and the evolution of tooth emergence and replacement patterns in primates and ungulates, p. 212-228. In Teaford, M.F., Meredith Smith, M., and Ferguson, M.W.J. (eds.), Development, Function and Evolution of Teeth. Cambridge University Press, Cambridge. https://doi.org/10.1017/CBO9780511542626.015 Smith, G.J. and DeSantis, L.R.G. 2018. Dietary ecology of Pleistocene mammoths and mastodons as inferred from dental microwear textures. Palaeogeography, Palaeoclimatology, Palaeoecology, 492:10-25. https://doi.org/10.1016/j.palaeo.2017.11.024 Solounias, N., Plavcan, M., Quade, J., and Witmer, L. 1999. The Pikermian Biome and the savanna myth, p. 427-444. In Agustı,́ J., Andrews, P., and Rook, L. (eds.), Evolution of the Neogene Terrestrial Ecosystems in Europe. Cambridge University Press, Cambridge Solounias, N. and Semprebon, G.M. 2002. Advances in the reconstruction of ungulate ecomorphology with application to early fossil equids. American Museum Novitates, 3366:1- 49. https://doi.org/10.1206/0003-0082(2002)366<0001:AITROU>2.0.CO;2 Solounias, N., Rivals, F., and Semprebon, G.M. 2010. Dietary interpretation and paleoecology of herbivores from Pikermi and Samos (late Miocene of Greece). Paleobiology, 36:113-136. https://doi.org/10.1666/0094-8373-36.1.113 Stearns, S.C. 1992. The Evolution of Life Histories. Oxford University Press, New York. Stebbins, G.L. 1981. Coevolution of Grasses and Herbivores. Annals of the Missouri Botanical Garden, 68:75-86. Stirton, R.A. 1947. Observations on evolutionary rates in hypsodonty. Evolution, 1:32-41. https://doi.org/10.1111/j.1558-5646.1947.tb02711.x 28 PALAEO-ELECTRONICA.ORG Strömberg, C.A.E. 2006. Evolution of hypsodonty in equids: testing a hypothesis of adaptation. Paleobiology, 32:236-258. https://doi.org/10.1666/0094-8373(2006)32[236:EOHIET]2.0.CO;2 Strömberg, C.A.E., Werdelin, L., Friis, E.M., and Saraç, G. 2007. The spread of grass-dominated habitats in Turkey and surrounding areas during the Cenozoic: Phytolith evidence. Palaeogeography, Palaeoclimatology, Palaeoecology, 250:18-49. https://doi.org/10.1016/j.palaeo.2007.02.012 Teaford, M.F. and Oyen, O.J. 1989. In vivo and in vitro turnover in dental microwear. American Journal of Physical Anthropology, 80:447-467. https://doi.org/10.1002/ajpa.1330800405 Teaford, M.F., Ungar, P.S., Taylor, A.B., Ross, C.F., and Vinyard, C.J. 2017. In vivo rates of dental microwear formation in laboratory primates fed different food items. Biosurface and Biotribology, 3:166-173. https://doi.org/10.1016/J.BSBT.2017.11.005 Tütken, T., Kaiser, T.M., Vennemann, T., and Merceron, G. 2013. Opportunistic feeding strategy for the earliest old world hypsodont equids: evidence from stable isotope and dental wear proxies. PLoS One, 8:e74463. https://doi.org/10.1371/journal.pone.0074463 Ungar, P.S., Brown, C.A., Bergstrom, T.S., and Walker, A. 2003. Quantification of dental microwear by tandem scanning confocal microscopy and scale-sensitive fractal analyses. Scanning, 25:185-193. https://doi.org/10.1002/sca.4950250405 Veiberg, V., Mysterud, A., Gaillard, J.M., Delorme, D., Van Laere, G., and Klein, F. 2007. Bigger teeth for longer life? Longevity and molar height in two roe deer populations. Biology Letters, 3:268-270. https://doi.org/10.1098/rsbl.2006.0610 Vlachou, T.D. 2013. Palaeontological, biostratigraphical and palaeoecological study of the Greek hipparions. PhD Thesis. Aristotle University of Thessaloniki, Greece. (In Greek with English summary) Wang, L., D’Odorico, P., Ries, L., and Macko, S.A. 2010. Patterns and implications of plant-soil δ13C and δ15N values in African savanna ecosystems. Quaternary Research, 73:77-83. https://doi.org/10.1016/j.yqres.2008.11.004 Winkler, D.E., van den Hoek Ostende, L.W., Schulz, E., Calandra, I., Gailer, J.P., Landwehr, C., and Kaiser, T.M. 2013. Dietary divergence in space and time - Lessons from the dwarf-goat Myotragus balearicus (Pleisto-Holocene, Mallorca, Spain). Mammalian Biology, 78:430-437. https://doi.org/10.1016/j.mambio.2013.08.003 Woodburne, M.O. 2009. Hippotherium (Mammalia, Equidae), p. 585-604. The early Vallesian vertebrates from Atzelsdorf (Austria, Late Miocene). Annalen des Naturhistorischen Museum Wien, 111A. Woodburne, M.O. 1989. Hipparion horses: a pattern of endemic evolution and intercontinental dispersal, p.197-233. In Prothero, D.R. and Schoch, R.M. (eds.), The Evolution of Perissodactyls. Oxford University Press, New York. Woodburne, M.O. and MacFadden, B.J. 1982. A reappraisal of the systematics, biogeography, and evolution of fossil horses. Paleobiology, 8:315-327. https://doi.org/10.1017/ S0094837300007077 29 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR APPENDICES APPENDIX 1. INFORMATION ON THE HIPPARIONIN SAMPLE. APPENDIX 1.1. Western Mediterranean The Vallesian hipparionins from the western Mediterranean area come from the fossil sites of Can Llobateres, Can Poncic and Santiga. All three localities are situated on the Vallès-Penedès Basin (northeastern Iberian Peninsula) (Figure 1, main text) and are placed on medial to distal facies of alluvial origin (Casanovas-Vilar et al., 2014). The classical fossil site of Can Llobateres registers the early/late Vallesian (MN9/MN10) transition and has been divided into two different levels with estimated ages of 9.72 Ma and 9.65 Ma, respectively (Casanovas-Vilar et al., 2011). Both Can Poncic and Santiga were dated on the early Vallesian with an estimated age of 10.4 to 9.9 Ma (Casanovas-Vilar et al., 2011). Based on a Vallesian hipparionin cranium of the Vallès- Penedès, Pirlot (1956) established the species Hipparion catalaunicum. Thereafter, Vallesian hipparionins from this basin have been generally assigned to this taxon. The similarities between this form with the central European Hipparion primigenium [= Hippotherium primigenium sensu Bernor et al. (1996)] (Forsten, 1968; Woodburne and Bernor, 1980) have led some authors to include it within the H. primigenium species (Forsten, 1968; Alberdi, 1974; Tomàs et al., 2010), and differentiate it at subspecific level (Alberdi, 1974; Tomàs et al., 2010). The presence of one single large species have been proposed in Can Poncic and Can Llobateres (Scott et al., 2013). We consider both populations to pertain to the H. primigenium catalaunicum subspecies follow- ing Tomàs et al. (2010). In Santiga, however, it is evident that at least two species are present, an abundant medium-sized to small hipparionin and a much rarer large one (Forsten, 1997). Although unnamed, the small/medium-sized hipparionin from Santiga represent a different taxon compared to larger Vallesian forms, although it might also be related to the primigenium group. Here we refer to this form as Hipparion sp. (?primigenium small). Due to the lack of dentognathic material of the large species from Santiga, we only analyze the microwear texture of the small hipparionin from this site. The Turolian material from this area come from the localities of Concud, El Arquillo and Venta del Moro. The classical fossil sites from Concud and El Arquillo are located in the Teruel Basin (cen- tral eastern Iberian Peninsula), and Venta del Moro in the Cabriel Basin (central eastern Iberian Peninsula) (Figure 1, main text). Both Concud and Venta del Moro sites were formed in marginal lacustrine environments with abundant vegetation (Montoya et al., 2006; Pesquero et al., 2013). The locality of Concud (MN12) has an estimated age of 7.2–7.1 Ma, while El Arquillo and Venta del Moro are dated on the MN13 with estimated ages of 6.2 Ma (van Dam et al., 2001) and 5.8– 5.5 Ma (Opdyke et al., 1997), respectively. Recently, however, a magnetostratigraphic study by Gibert et al. 2013 dated Venta del Moro at 6.23 Ma. Still, El Arquillo site is deemed to be older because of the absence of Paraethomys miocaenicus, similarly to Las Casiones, which was dated at 6.33 Ma (van Dam, 1997; van Dam et al., 2006). During the middle Turolian (MN12) the most common species was Hipparion concudense, a medium to large sized hipparionin [178 kg (Pesquero and Alberdi, 2012)] that is very abundant in Concud (Pesquero and Alberdi, 2012). On the other hand, at least three different sized hipparionins inhabited the Teruel Basin during the late Turolian (MN13). The three sympatric taxa identified in El Arquillo have been referred to Hipparion periafricanum, Hipparion gromovae, and H. primigenium truyolsi (Alberdi, 1974). The two dwarf hipparionins of this site, H. periafricanum and H. gromovae, are the smallest members of this clade in the Iberian Peninsula (Ortiz-Jaureguizar and Alberdi, 2003; Pesquero, 2003). H. primigenium truyolsi, on the other hand, was much larger (Ortiz-Jaureguizar and Alberdi, 2003). An association of three sympatric forms has also been reported in the Venta del Moro. Morpho- metric comparisons of the most common hipparionin from this site has allowed its assignment to the species Hipparion matthewi (Pesquero et al., 2007), which is also present in eastern Mediter- ranean basins. This identification, however, has recently been questioned (Koufos, 2016b; Kou- fos and Vlachou, 2016), so here we decided to refer this medium-sized hipparionin as H. cf. matthewi and to differentiate it from the eastern Mediterranean forms. Pesquero et al. (2007), based on the material from Venta del Moro, also proposed the synonymy of H. gromovae and H. matthewi. Because we are interested in testing dietary differences related to size, the body mass differences between H. gromovae from El Arquillo (84 kg) and H. cf. matthewi from Venta del Moro (123 kg) (Table 1, main text), together with the lack of cranial traits to compare, make us 30 PALAEO-ELECTRONICA.ORG consider both populations two different sets of data. Besides H. cf. matthewi, there are two other hipparionins present in Venta del Moro: a much rarer large form determined as H. primigenium, and a probable smaller subspecies of H. cf. matthewi (Pesquero et al., 2007). Due to the scarcity of remains assigned to these two last forms, here we only analyze the microwear texture of the medium-sized H. cf. matthewi from Venta del Moro. All the hipparionin teeth and mandibles from western Mediterranean sites are stored at the collections of the Institut Català de Paleontologia Miquel Crusafont (ICP), Barcelona, and of the Museo Nacional de Ciencias Naturales (MNCN), Madrid. APPENDIX 1.2. Balkans The Vallesian hipparionins pertain to the localities of Ravin de la Pluie and Pentalophos from the Axios Valley (southeastern Balkan Peninsula), and to Nikiti-1, which is located in the Chalkidiki Peninsula (southeastern Balkan Peninsula) (Figure 1, main text). Ravin de la Pluie was dated to the lower part of the late Vallesian (MN10) with an estimated age of ~9.3 Ma based on a combi- nation of biochronological and paleomagnetostratigraphical data (Sen et al., 2000; Koufos, 2006a). Nikiti-1 is correlated based on its mammalian assemblage to the upper part of the late Vallesian with an estimated age ranging from 9.3 to 8.7 Ma (Koufos, 2006b, 2016a). Pentalo- phos’ chronology is not clear, although its faunal association indicates that it could be slightly older than Ravin de la Pluie (Koufos, 2006a, 2006b, 2013). Following Vlachou (2013), two hippa- rionin morphotypes were present in Macedonia during the Vallesian: the small macedonicum and the large primigenium morphotype. The material of the small macedonicum morphotype has been assigned to the Hipparion macedonicum species, while the larger hipparionins of the primi- genium morphotype have been referred to Hipparion aff. giganteum in Nikiti-1, and to Hipparion cf. sebastopolitanum in Pentalophos and Ravin de la Pluie (Koufos et al., 2016; Vlachou, 2013). Numerous Turolian localities have yielded rich hipparionin assemblages in the Balkan region. The Turolian sample analyzed here comes from the localities of Nikiti-2, Ravin des Zouaves-5, Hadjidimovo, Perivolaki and Dytiko. The oldest fossil site is Nikiti-2 (Chalkidiki Peninsula) (Figure 1, main text), dated to the early Turolian (MN11) with an age comprised between 8.7–8.2 Ma (Koufos, 2016a). Four different hipparionins are recognized here: two small taxa of the macedon- icum morphotype (Hipparion sithonis and H. macedonicum), a larger form that pertains to the dietrichi morphotype (Hipparion philippus), and a rare and large hipparionin of the proboscideum group identified as Hipparion cf. proboscideum (Vlachou, 2013; Koufos and Vlachou, 2016). Ravin des Zouaves-5 (Axios Valley) is also an early Turolian site (MN11) dated at ~8.2 Ma (Kou- fos, 2006b). In this locality, Koufos and Vlachou (2019) reported five different taxa: H. macedoni- cum and H. sithonis of the macedonicum morphotype, H. proboscideum and H. cf. mediterraneum of the proboscideum morphotype, and H. philippus of the dietrichi morphotype. From this site, here we analyzed mainly specimens of H. macedonicum due to their availability. Hadjidimovo locality (Mesta Valley, central Balkan Peninsula) (Figure 1, main text) was dated between the early-middle Turolian (MN11–MN12) with an estimated age of ~7.5 Ma (Spassov, 2002). Three species have been identified, although the major bulk of the material corresponds to the two large species Hipparion mediterraneum [proboscideum morphotype sensu Vlachou (2013)] and Hipparion brachypus [primigenium morphotype sensu Vlachou (2013)] (Hristova, 2009), which are the species herein analyzed. We also sampled the hipparionins from Perivolaki (Thessaly, southeastern Balkan Peninsula) (Figure 1, main text), a site dated on the upper mid- dle Turolian (MN12) with an estimated age of 7.3–7.1 Ma (Koufos, 2006a, 2006b). In Perivolaki, three different species are found: H. macedonicum, H. philippus and H. proboscideum; forming a similar association than other early and middle Turolian sites from the Axios Valley. Finally, the youngest locality is represented by the three Dytiko sites (DKO, DTK, DIT; Axios Valley) (Figure 1, main text), which were dated to the late Turolian (MN13) (Koufos, 2006b). Three hipparionin taxa are identified in the Dytiko faunal assemblage: the large Hipparion aff. platygenys [dietrichi morphotype sensu Vlachou (2013)], the small Hipparion cf. macedonicum, and a medium-sized rare form resembling to Hipparion moldavicum and tentatively assigned to the proboscideum morphotype (Vlachou, 2013). Because of the scarcity of some of the material from the species mentioned, we did not consider for analysis the proboscideum group from Nikiti-2 nor from the Dytiko sites, and only include one specimen from Ravin des Zouaves-5. The fossil material ana- lyzed here from Hadjidimovo is stored at the Asenovgrad Museum (a division of the National Museum of Natural History of Sofia, Bulgaria) and the specimens from the Greek localities come from the Laboratory of Geology and Paleontology, Aristotle University of Thessaloniki, Greece. 31 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR APPENDIX 1.3. Western Anatolia The Turolian hipparionins from the western Anatolian bioprovince come from the localities of Şerefköy-2, Gülpınar and the Samos new collections. The specimens from Samos pertain to the MTLA/B sites found in the Adrianos ravine during the recent excavations (Mytilinii Basin, Samos Island) (Figure 1, main text), which were dated on the late middle Turolian (~7.1 Ma) (Koufos et al., 2009; Vlachou and Koufos, 2009). At least five hipparionin taxa pertaining to four different morphotypes are present there: H. cf. matthewi (macedonicum morphotype), Hipparion aff. for- stenae (proboscideum morphotype), H. cf. proboscideum (proboscideum morphotype), H. dietri- chi (dietrichi morphotype) and H. brachypus (primigenium morphotype) (Vlachou and Koufos, 2009; Vlachou, 2013). In the Anatolian Peninsula, the locality of Şerefköy-2 (Muğla Yatağan Basin, western Anatolia) (Figure 1, main text) has been referred to the middle Turolian (MN12) based on its fossil mammal assemblage (Kaya et al., 2012). Four to five different hipparionin forms might be present in this site, a rare and large species similar to H. brachypus, two medium hipparionins broadly referred as Hipparion, and two small forms only identified as belonging to the Cremohipparion group [sensu Bernor et al. (1996)] (Kaya et al., 2012). The medium-sized hipparionins show similarities to H. mediterraneum specimens (Kaya et al., 2012). In conse- quence, we included here the medium sized forms to the proboscideum group. We further relate the small hipparionins of Şerefköy-2 to the species H. matthewi, as it has been done with the majority of the small-sized forms from eastern Mediterranean basins (Koufos, 2016b), thus including them to the macedonicum group defined by Vlachou (2013). Finally, Gülpınar fossil site is located on the Biga Peninsula (northwestern Anatolia) (Figure 1, main text) and corresponds to a sedimentary sequence of fluvial origin dated on early-middle Turolian (MN11–MN12) (For- sten and Kaya, 1995; Koufos et al., 2018). Three different forms have been distinguished in Gülpınar. The smallest hipparionin has been identified as H. cf. matthewi (macedonicum mor- photype) and the medium-sized form show affinities to H. dietrichi from the classic Samos quar- ries (Forsten and Kaya, 1995). Due to these similarities, here we include this form to the dietrichi group defined by Vlachou (2013). The larger hipparionin remains from Gülpınar have not been determined. We did not analyze the dental microwear textures of the largest taxon—usually related to H. brachypus (Vlachou and Koufos, 2009; Kaya et al., 2012)—from the western Anato- lian fossil sites due to its scarcity. The material from Samos is stored at the Paleontological Museum of Mytilinii, Samos, Greece, and the material from continental Anatolian sites at the Nat- ural History Museum of Ege University of Izmir, Turkey. APPENDIX 1.4. References Alberdi, M.T. 1974. Las “faunas de Hipparion” de los yacimientos españoles. Estudios Geológicos, 30:189–212. Bernor, R.L., Koufos, G.D., Woodburne, M.O., and Fortelius, M. 1996. The evolutionary history and biochronology of European and Southwest Asian Late Miocene and Pliocene hipparionine horses, p. 307-338. In Bernor, R.L., Fahlbusch, V., and Mittmann, H.-W. (eds.), The Evolution of Western Eurasian Neogene Mammal Faunas. Columbia University Press, New York. Casanovas-Vilar, I., Alba, D.M., Garcés, M., Robles, J.M., and Moyà-Solà, S. 2011. Updated chronology for the Miocene hominoid radiation in Western Eurasia. Proceedings of the National Academy of Sciences of the United States of America, 108:5554–9. https://doi.org/ 10.1073/pnas.1018562108 Casanovas-Vilar, I., Van den Hoek Ostende, L.W., Furió, M., and Madern, P.A. 2014. The range and extent of the Vallesian Crisis (Late Miocene): New prospects based on the micromammal record from the Vallès-Penedès basin (Catalonia, Spain). Journal of Iberian Geology, 40:29– 48. https://doi.org/10.5209/rev_JIGE.2014.v40.n1.44086 Forsten, A. 1968. Revision of the palearctic Hipparion. Acta Zoologica Fennica, 119:1-134. Forsten, A. 1997. Hipparion from Santiga (Spain) and its biostratigraphic significance. Paleontologia i Evolució, 30-31:77–82. Forsten, A. and Kaya, T. 1995. The hipparions (Mammalia, Equidae) from Gülpinar (Canakkale, Turkey). Paläontologische Zeitschrift, 69:491–501. https://doi.org/10.1007/BF02987809 Gibert, L., Scott, R., G., Montoya, P., Ruiz-Sánchez, J.F., Morales, J., Luque, L., Abella, J. and Lería, M. 2013. Evidence for an African-Iberian mammal dispersal during the pre-evaporitic Messinian. Geology, 41:691–694. https://doi.org/10.1130/g34164.1 32 PALAEO-ELECTRONICA.ORG Hristova, L. 2009. Ontogeny and variability in the cheek region of hipparions from the late Miocene locality of Hadzhidimovo-1, southwest Bulgaria. Rivista Italiana di Paleontologia e Stratigrafia, 115:125-132. https://doi.org/10.13130/2039-4942/5924 Kaya, T., Mayda, S., Kostopoulos, D.S., Alcicek, M.C., Merceron, G., Tan, A., Karakutuk, S., Giesler, A.K., and Scott, R.S. 2012. Şerefköy-2, a new Late Miocene mammal locality from the Yataĝan Formation, Muĝla, SW Turkey. Comptes Rendus – Palevol,11:5–12. https://doi.org/10.1016/j.crpv.2011.09.001 Koufos, G.D. 2006a. Palaeoecology and chronology of the Vallesian (late Miocene) in the Eastern Mediterranean region. Palaeogeography, Palaeoclimatology, Palaeoecology, 234:127–145. https://doi.org/10.1016/j.palaeo.2005.01.014 Koufos, G.D. 2006b. The Neogene mammal localities of Greece: Faunas, chronology and biostratigraphy. Hellenic Journal of Geosciences, 41:183–214. Koufos, G.D. 2013. Neogene mammal biostratigraphy and chronology of Greece, p. 595-621. In Wang, X., Flynn, L.J., and Fortelius, M. (eds.), Fossil Mammals of Asia—Neogene Biostratigraphy and Chronology. Columbia University Press, New York. Koufos, G.D. 2016a. History, stratigraphy and fossiliferous sites, p. 3-10. In Koufos G.D. and Kostopoulos, D.S. (eds.), Palaeontology of the Upper Miocene Vertebrate Localities of Nikiti (Chalkidiki Peninsula, Macedonia, Greece).Geobios, 49. https://doi.org/10.1016/j.geobios.2016.01 Koufos, G.D. 2016b. Hipparion macedonicum revisited: New data on evolution of hipparionine horses from the Late Miocene of Greece. Acta Palaeontologica Polonica, 61:519–536. https://doi.org/10.4202/app.00169.2015 Koufos, G.D., Kostopoulos, D.S., and Merceron, G. 2009. Palaeoecology – Palaeobiogeography, p. 409-430. In Koufos, G.D. and Nagel, D. (eds.), The late Miocene Mammal Faunas of the Mytilinii Basin, Samos Island, Greece: new collection. Beiträge zur Paläontologie, 31. Koufos, G.D., Kostopoulos, D.S., and Vlachou, T.D. 2016. Revision of the Nikiti 1 (NKT) fauna with description of new material, p. 11-22. In Koufos G.D. and Kostopoulos, D.S. (eds.), Palaeontology of the Upper Miocene Vertebrate Localities of Nikiti (Chalkidiki Peninsula, Macedonia, Greece).Geobios, 49. https://doi.org/10.1016/j.geobios.2016.01.006 Koufos, G.D., Mayda, S., and Kaya, T. 2018. New carnivoran remains from the Late Miocene of Turkey. Paläontologische Zeitschrift, 92:131–162. https://doi.org/10.1007/s12542-017-0376-2 Koufos, G.D., Vlachou, T.D., 2016. Equidae, p. 85–118. In Koufos G.D. and Kostopoulos, D.S. (eds.), Palaeontology of the Upper Miocene Vertebrate Localities of Nikiti (Chalkidiki Peninsula, Macedonia, Greece).Geobios, 49. https://doi.org/10.1016/j.geobios.2016.01.001 Koufos, G.D. and Vlachou, T.D. 2019. New material and revision of hipparions from the Upper Miocene locality Ravin des Zouaves-5, RZO of Axios Valley (Macedonia, Greece). Geobios, 57:33-52. https://doi.org/10.1016/j.geobios.2019.10.004 Montoya, P., Morales, J., Robles, F., Abella, J., Benavent, J. V, Marín, M. D., and Ruiz Sánchez, F.J. 2006. Las nuevas excavaciones (1995-2006) en el yacimiento del Mioceno final de Venta del Moro, Valencia. Estudios Geológicos, 62:313–326. Opdyke, N., Mein, P., Lindsay, E., Perez-Gonzales, A., Moissenet, E., and Norton, V.L. 1997. Continental deposits, magnetostratigraphy and vertebrate paleontology, late Neogene of eastern Spain. Palaeogeography, Palaeoclimatology, Palaeoecology, 133:129–148. https://doi.org/10.1016/S0031-0182(97)00080-1 Ortiz-Jaureguizar, E. and Alberdi, M.T. 2003. El patrón de cambios en la masa corporal de los Hipparionini (Perissodactyla, Equidae) de la Península Ibérica durante el Mioceno superior- Plioceno superior. Coloquios de Paleontología, 1:499–509. Pesquero, M.D. 2003. Hipparion del Turoliense superior de Las Casiones (Fosa de Teruel). Coloquios de Paleontología, Volumen Ex:511–548. Pesquero, M.D. and Alberdi, M.T. 2012. New evidence of conspecificity between Hipparion primigenium melendezi Alberdi, 1974 from Los Valles de Fuentidueña (Segovia) and Hipparion concudense concudense Pirlot, 1956 from Concud (Teruel) Spain. Estudios Geológicos 68:247–260. https://doi.org/10.3989/egeol.40499.152 33 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR Pesquero, M.D., Alberdi, M.T., and Montoya, P. 2007. Hipparion (Equidae, Mammalia) from Venta del Moro (Valencia Province, Spain). Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen, 243:273–297. https://doi.org/10.1127/0077-7749/2007/0243-0273 Pesquero, M.D., Alcalá, L., and Fernández-Jalvo, Y. 2013. Taphonomy of the reference Miocene vertebrate mammal site of Cerro de la Garita, Spain. Lethaia 46:378–398. https://doi.org/10.1111/let.12016 Pirlot, P.L. 1956. Les Formes Européennes du genre Hipparion. Consejo Superior de Investigaciones Científicas, Barcelona. Scott, R.S., Clavel, J., DeMiguel, D., Kaya, T., Kostopoulos, D.S., Mayda, S., and Merceron, G. 2013. Ecology of european hipparionines and the diversity of late Miocene hominids in western Eurasia, 14th RCMN Congress Neogene to Quaternary Geological Evolution of Mediterranean, Paratethys and Black Sea. Istanbul, p. 262. Sen, S., Kondopoulou, D., and de Bonis, L. 2000. Magnetostratigraphy of Late Miocene continental deposits of the Lower Axios valley, Macedonia, Geological Society of Greece. Special Publications, 9:197-206. Spassov, N. 2002. The Turolian megafauna of west Bulgaria and the character of the Late Miocene “Pikermian biome“. Bollettino della Società Paleontologica Italiana, 41:69–81. Tomàs, M., Alba, D.M., Sanisidro, Ó., and Bolet, A. 2010. Los perisodáctilos del Mioceno superior de la autovía orbital de Barcelona B-40, tramo Olesa de Montserrat - Viladecavalls (Cuenca del Vallès-Penedès). Cidaris, 30:317–323. van Dam, J. 1997. The small mammals from the Upper Miocene of the Teruel-Alfambra region (Spain): paleobiology and paleoclimatic reconstructions. Geologica Ultraiectina, 156: 1-204. van Dam, J., Abdul Aziz, H., Álvarez Sierra, M.A., Hilgen, F.J., Van Den Hoek Ostende, L.W., Lourens, L.J., Mein, P., Van Der Meulen, A.J., and Pelaez-Campomanes, P., 2006. Long- period astronomical forcing of mammal turnover. Nature, 443:687–691. https://doi.org/10.1038/nature05163 van Dam, J.A., Alcalá, L., Zarza, A.A., Calvo, J.P., Garcés, M., and Krijgsman, W. 2001. The upper Miocene mammal record from the Teruel-Alfambra region (Spain). The MN system and continental stage/age concepts discussed. Journal of Vertebrate Paleontology, 21:367–385. https://doi.org/10.1671/0272-410.1671/0272-4634(2001)021[0367:TUMMRF]2.0.CO;2 Vlachou, T.D. 2013. Palaeontological, biostratigraphical and palaeoecological study of the Greek hipparions. PhD Thesis. Aristotle University of Thessaloniki, Greece. (in Greek with English summary). Vlachou, T.D. and Koufos, G.D. 2009. Equidae, p. 207–281 In Koufos, G.D. and Nagel, D. (eds.), The late Miocene Mammal Faunas of the Mytilinii Basin, Samos Island, Greece: new collection. Beiträge zur Paläontologie, 31. Woodburne, M.O. and Bernor, R.L. 1980. On superspecific groups of some Old World hipparionine horses. Journal of Paleontology, 54:1319–1348. 34 PALAEO-ELECTRONICA.ORG APPENDIX 2. RAW DATA OF ALL THE HIPPARIONIN SAMPLE ANALYZED. Orlandi-Oliveras, Guillem (2022), “Appendices for: Feeding strategies of circum-Mediterranean hipparionins during the late Miocene: exploring dietary preferences related to size through Den- tal Microwear Analysis”, Mendeley Data, V1. https://data.mendeley.com/datasets/np65bh8tgw/2 APPENDIX 3. PHOTOSIMULATIONS OF THE MICROWEAR SURFACES. Orlandi-Oliveras, Guillem (2022), “Appendices for: Feeding strategies of circum-Mediterranean hipparionins during the late Miocene: exploring dietary preferences related to size through Den- tal Microwear Analysis”, Mendeley Data, V1. https://data.mendeley.com/datasets/np65bh8tgw/2 APPENDIX 4. Results of the Principal Component Analysis performed with the ten settings used to calculate HAsfc (4, 9, 16, 25, 36, 49, 64, 81, 100, and 121 cells). Percentage of variance explained by the principal component and the contribution of each setting to the principal components are shown. Component % of variance H4 H9 H16 H25 H36 H49 H64 H81 H100 H121 PC1 84.31 5.11 8.26 9.87 10.69 11.06 11.09 11.15 10.99 10.89 10.89 PC2 7.88 60.94 15.86 3.57 0.02 0.62 2.46 2.68 4.66 5.18 4.03 APPENDIX 5. METAPODIAL MEASURES AND BODY MASS ESTIMATIONS. Orlandi-Oliveras, Guillem (2022), “Appendices for: Feeding strategies of circum-Mediterranean hipparionins during the late Miocene: exploring dietary preferences related to size through Den- tal Microwear Analysis”, Mendeley Data, V1. https://data.mendeley.com/datasets/np65bh8tgw/2 35 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR APPENDIX 6. LINEAR REGRESSIONS ON DMT PARAMETERS VERSUS BODY MASS. APPENDIX 6.1. Linear regressions of microwear textural parameters and the calculated princi- pal component against body mass for all hipparionins. Correlation statistics included in each graph. A: Regression of the Asfc values. B: epLsar. C: HAsfc. D: Tfv. E: PC1. 36 PALAEO-ELECTRONICA.ORG APPENDIX 6.2. Linear regressions of microwear textural parameters and the calculated princi- pal component against body mass for western Mediterranean hipparionins. Correlation statistics included in each graph. A: Regression of the Asfc values. B: epLsar. C: HAsfc. D: Tfv. E: PC1. 37 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR APPENDIX 6.3. Linear regressions of microwear textural parameters and the calculated princi- pal component against body mass for hipparionins from the Balkans. Correlation statistics included in each graph. A: Regression of the Asfc values. B: epLsar. C: HAsfc. D: Tfv. E: PC1. 38 PALAEO-ELECTRONICA.ORG APPENDIX 6.4. Linear regressions of microwear textural parameters and the calculated princi- pal component against body mass for western Anatolian hipparionins. Correlation statistics included in each graph. A: Regression of the Asfc values. B: epLsar. C: HAsfc. D: Tfv. E: PC1. 39 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR APPENDIX 7. POST-HOC PAIRWISE COMPARISONS WITH TUROLIAN HIPPARIONIN DATA. APPENDIX 7.1. Post-hoc tests on ranked complexity (Asfc). P-values from HSD test are depicted above the grey diagonal and those from LSD are under it. Significant p-values repre- sented in bold. BIOPROVINCE Western Mediterranean Balkans Western Anatolia Western Mediterranean < 0.001 0.001 Balkans < 0.001 0.011 Western Anatolia < 0.001 0.004 APPENDIX 7.2. Post-hoc tests on ranked heterogeneity of complexity (HAsfc). P-values from HSD test are depicted above the grey diagonal and those from LSD are under it. Significant p- values represented in bold. BIOPROVINCE Western Mediterranean Balkans Western Anatolia Western Mediterranean 0.049 0.935 Balkans 0.019 0.189 Western Anatolia 0.727 0.081 40 PALAEO-ELECTRONICA.ORG APPENDIX 7.3. Summary of post-hoc tests on ranked parameters showing significant differ- ences between the Turolian hipparionin groups. Significant differences between groups obtained from HSD test are depicted above the grey diagonal and those from LSD are under it. Bioprovince West Mediterranean Balkans Western Anatolia proboscideum proboscideum macedonicum macedonicum periafricanum primigenium primigenium concudense cf. matthewi Turolian gromovae dietrichi dietrichi hipparionin groups periafricanum epLsar Asfc, epLsar, PC1 Western Mediterranean gromovae Asfc, Asfc epLsar, PC1 cf. matthewi Asfc, Asfc, Asfc Asfc Asfc, Asfc, Asfc, Asfc epLsar, epLsar, PC1 PC1 PC1 PC1 PC1 concudense Asfc, Asfc, Asfc, Asfc, Asfc, Asfc, Asfc, PC1 Asfc, epLsar, epLsar, PC1 PC1 PC1 HAsfc, PC1 PC1 PC1 PC1 PC1 primigenium HAsfc HAsfc HAsfc macedonicum Asfc, Asfc, Asfc, PC1 Asfc, Asfc, HAsfc epLsar epLsar, PC1 dietrichi Asfc, Asfc, epLsar, Asfc, HAsfc, PC1 epLsar, PC1 Balkans proboscideum epLsar, Asfc, Asfc, HAsfc, Asfc, Asfc, HAsfc, PC1 HAsfc PC1 HAsfc, PC1 epLsar, HAsfc, PC1 PC1 HAsfc, PC1 PC1 primigenium epLsar HAsfc Asfc, HAsfc, Asfc, HAsfc HAsfc HAsfc HAsfc PC1 epLsar, HAsfc, PC1 macedonicum Asfc, PC1 Asfc, HAsfc HAsfc epLsar, Western Anatolia PC1 dietrichi Asfc, HAsfc, Asfc, HAsfc Asfc, Asfc HAsfc PC1 epLsar, HAsfc HAsfc, PC1 proboscideum epLsar Asfc, PC1 Asfc, Asfc Asfc, HAsfc HAsfc epLsar, HAsfc, PC1 PC1 41 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR APPENDIX 7.4. Summary of post-hoc tests on parameters showing significant differences between localities. Here represented the results from pairwise comparisons between localities with hipparionins of the macedonicum group. Significant differences obtained from the HSD test are above the grey diagonal and those from LSD are under it. macedonicum group Balkans Western Anatolia Locality NIK RZO PER DTK GLP MYSE MTLA/B Nikiti-2 (NIK) epLsar Ravin des Zouaves-5 epLsar Balkans (RZO) Perivolaki (PER) epLsar, PC1 Dytiko (DTK) epLsar, PC1 Tfv Western Gülpınar (GLP) HAsfc, PC1 HAsfc HAsfc HAsfc Anatolia Şerefköy-2 (MYSE) epLsar Tfv HAsfc Samos (MTLA/B) Tfv HAsfc APPENDIX 7.5. Summary of post-hoc tests on parameters showing significant differences between localities. Here represented the results from pairwise comparisons between localities with hipparionins of the dietrichi group. Significant differences obtained from the HSD test are above the grey diagonal and those from LSD are under it. dietrichi group Balkans Western Anatolia Locality NIK PER DTK GLP MTLA/B Nikiti-2 (NIK) Balkans Perivolaki (PER) epLsar, PC1 Dytiko (DTK) Western Gülpınar (GLP) Anatolia Samos (MTLA/B) epLsar APPENDIX 7.6. Summary of post-hoc tests on parameters showing significant differences between localities. Here represented the results from pairwise comparisons between localities with hipparionins of the proboscideum group. Significant differences obtained from the HSD test are above the grey diagonal and those from LSD are under it. proboscideum group Balkans Western Anatolia Locality RZO PER HD MYSE MTLA/B Ravin des Zouaves-5 (RZO) Balkans Perivolaki (PER) Tfv Hadjidimovo (HD) Western Şerefköy-2 (MYSE) HAsfc Anatolia Samos (MTLA/B) Tfv, PC1 HAsfc, PC1 Tfv APPENDIX 7.7. Summary of post-hoc tests on parameters showing significant differences between localities. Here represented the results from pairwise comparisons between localities with hipparionins of the primigenium group. Significant differences obtained from the HSD test are above the grey diagonal and those from LSD are under it. primigenium group Western Mediterranean Balkans Locality ARQ HD Western Mediterranean El Arquillo (ARQ) HSD test → Balkans Hadjidimovo (HD) HAsfc ← LSD test 42 PALAEO-ELECTRONICA.ORG APPENDIX 7.8. Results of the post-hoc tests from pairwise comparisons between hipparionin groups from Nikiti-2 locality. Nikiti-2 (NIK) macedonicum dietrichi Asfc: - epLSar: 1.000 macedonicum HSD test → HAsfc: 1.000 Tfv: 1.000 PC1: 1.000 Asfc: - epLSar: 0.968 dietrichi HAsfc: 0.480 ← LSD test Tfv: 0.667 PC1: 0.811 APPENDIX 7.9. Results of the post-hoc tests from pairwise comparisons between hipparionin groups from Perivolaki locality. Perivolaki (PER) macedonicum dietrichi proboscideum Asfc: - Asfc: - epLSar: 1.000 epLSar: 1.000 macedonicum HSD test → HAsfc: 1.000 HAsfc: 1.000 Tfv: 1.000 Tfv: 1.000 PC1: 1.000 PC1: 1.000 Asfc: - Asfc: - epLSar: 0.813 epLSar: 1.000 dietrichi HAsfc: 0.569 HAsfc: 1.000 Tfv: 0.997 Tfv: 1.000 PC1: 0.389 PC1: 1.000 Asfc: - Asfc: - epLSar: 0.744 epLSar: 0.669 proboscideum HAsfc: 0.779 HAsfc: 0.997 ← LSD test Tfv: 0.184 Tfv: 0.198 PC1: 0.203 PC1: 0.408 APPENDIX 7.10. Results of the post-hoc tests from pairwise comparisons between hipparionin groups from Hadjidimovo locality. Hadjidimovo (HD) proboscideum primigenium Asfc: - epLSar: 1.000 proboscideum HSD test → HAsfc: 1.000 Tfv: 1.000 PC1: 1.000 Asfc: - epLSar: 0.970 primigenium HAsfc: 0.990 ← LSD test Tfv: 0.257 PC1: 0.187 43 ORLANDI-OLIVERAS ET AL.: HIPPARIONIN DENTAL MICROWEAR APPENDIX 7.11. Results of the post-hoc tests from pairwise comparisons between hipparionin groups from Dytiko locality. Significant p-values represented in bold. Dytiko (DTK) macedonicum dietrichi Asfc: - epLSar: 0.998 macedonicum HSD test → HAsfc: 1.000 Tfv: 0.913 PC1: 1.000 Asfc: - epLSar: 0.144 dietrichi HAsfc: 0.806 ← LSD test Tfv: 0.040 PC1: 0.323 APPENDIX 7.12. Results of the post-hoc tests from pairwise comparisons between hipparionin groups from Gülpınar locality. Gülpınar (GLP) macedonicum dietrichi Asfc: - epLSar: 1.000 macedonicum HSD test → HAsfc: 1.000 Tfv: 1.000 PC1: 1.000 Asfc: - epLSar: 0.991 dietrichi HAsfc: 0.448 ← LSD test Tfv: 0.444 PC1: 0.516 APPENDIX 7.13. Results of the post-hoc tests from pairwise comparisons between hipparionin groups from Samos new collections. Samos (MTLA/B) macedonicum dietrichi proboscideum Asfc: - Asfc: - epLSar: 1.000 epLSar: 1.000 macedonicum HSD → HAsfc: 1.000 HAsfc: 0.971 Tfv: 1.000 Tfv: 1.000 PC1: 1.000 PC1: 0.995 Asfc: - Asfc: - epLSar: 0.663 epLSar: 1.000 dietrichi HAsfc: 0.353 HAsfc: 1.000 Tfv: 0.850 Tfv: 1.000 PC1: 0.691 PC1: 1.000 Asfc: - Asfc: - epLSar: 0.475 epLSar: 0.213 proboscideum HAsfc: 0.066 HAsfc: 0.479 ← LSD Tfv: 0.902 Tfv: 0.723 PC1: 0.111 PC1: 0.267 44 PALAEO-ELECTRONICA.ORG APPENDIX 7.14. Results of the post-hoc tests from pairwise comparisons between hipparionin groups from Şerefköy-2 locality. Şerefköy-2 (MYSE) macedonicum proboscideum Asfc: - epLSar: 1.000 macedonicum HSD test → HAsfc: 0.997 Tfv: 1.000 PC1: 1.000 Asfc: - epLSar: 0.972 proboscideum HAsfc: 0.124 ← LSD test Tfv: 0.881 PC1: 0.659 APPENDIX 7.15. Results of the post-hoc tests from pairwise comparisons between hipparionin groups from El Arquillo locality. Significant p-values represented in bold. El Arquillo (ARQ) periafricanum gromovae primigenium Asfc: - Asfc: - epLSar: 1.000 epLSar: 0.995 periafricanum HSD → HAsfc: 1.000 HAsfc: 0.840 Tfv: 1.000 Tfv: 1.000 PC1: 1.000 PC1: 1.000 Asfc: - Asfc: - epLSar: 0.175 epLSar: 1.000 gromovae HAsfc: 0.645 HAsfc: 0.909 Tfv: 0.779 Tfv: 0.985 PC1: 0.743 PC1: 1.000 Asfc: - Asfc: - epLSar: 0.112 epLSar: 0.397 primigenium HAsfc: 0.027 HAsfc: 0.039 ← LSD Tfv: 0.970 Tfv: 0.830 PC1: 0.604 PC1: 0.450 45