439 GEODIVERSITAS • 2001 • 23 (3) © Publications Scientifiques du Muséum nation

439 GEODIVERSITAS • 2001 • 23 (3) © Publications Scientifiques du Muséum national d’Histoire naturelle, Paris. www.mnhn.fr/publication/ New data on the Equus stenonis Cocchi, 1867 from the late Pliocene locality of Sésklo (Thessaly, Greece) Athanassios ATHANASSIOU University of Athens, Department of Historical Geology and Palaeontology, Panepistimiopolis, 157 84 Athens (Greece) aathan@cc.uoa.gr Athanassiou A. 2001. — New data on the Equus stenonis Cocchi, 1867 from the late Pliocene locality of Sésklo (Thessaly, Greece). Geodiversitas 23 (3): 439-469. ABSTRACT The equid material from the late Pliocene locality of Sésklo (Thessaly, Greece) is described and compared in this article. It belongs to a large and fairly stout Equus stenonis form, which shares many morphological characters with the species samples from Saint-Vallier, La Puebla de Valverde and Olivola, as well as with already known Equus stenonis samples from other Greek localities (Dafneró, Vólax). Its main features are the big skull and limbs, the short protocones and the very simple enamel plication in the teeth. Large sized and relatively robust stenonid horses are common elements of the late Pliocene faunas of Greece. RÉSUMÉ Nouvelles données sur l ’Equus stenonis Cocchi, 1867 de la localité pliocène de Sésklo (Thessalie, Grèce). Dans l’article présent, l’équidé de la localité pliocène de Sésklo (Thessalie, Grèce) est décrit et comparé. Il appartient à une forme d’Equus stenonis large et assez robuste, qui a des caractères morphologiques communs avec les échantillons de Saint-Vallier, La Puebla de Valverde et Olivola, ainsi qu’avec des échantillons déjà connus d’autres localités grecques (Dafneró et Vólax). Ses caractères morphologiques principaux s’observent sur le crâne et sur les membres de grandes dimensions, les protocônes sont courts et l’émail den- taire est faiblement plissé. Les équidés sténoniens grands et relativement robustes sont fréquents dans les faunes grecques du Pliocène supérieur. KEY WORDS Mammalia, Perissodactyla, Equidae, Equus stenonis, late Pliocene, Villafranchian, Thessaly, Greece. MOTS CLÉS Mammalia, Perissodactyla, Equidae, Equus stenonis, Pliocène supérieur, Villafranchien, Thessalie, Grèce. INTRODUCTION The site of Sésklo (Magnesia, Thessaly, Greece) (Fig. 1) is located in a basin filled with fluvio- lacustrine clay sediments. It is situated about 10 km West of the town of Vólos, the capital of the district of Magnesia. The basement of the basin is formed of metamorphic rocks (peri- dotites, serpentinites and slates with marble and ophiolite intercalations) that tectonically overlie a formation of Jurassic slates and Triassic-Jurassic marbles (Müller 1983; Symeonidis & Tataris 1983; Mastoras 1985). The clays that fill the basin are red coloured, about 100 m thick and inclined to the SE. Lithologically they are very uniform; only the uppermost layers have some pebble intercalations. A part of the basin is used by the local cement industry as a clay pit. The first findings in the site (some Anancus remains) were discovered in 1971 during the works in this pit (Symeonidis & Tataris 1983). Another discovery in 1982, followed by a brief excavation by Prof. N. Symeonidis (University of Athens), yielded most of the material. The present author also car- ried out a minor excavation in 1991. The exact location of each excavation in the site is different (Fig. 2), following the quarry development, which brought the fossils to light. The strati- graphic relationship of the different localities is not clear, due to the petrographic uniformity of the clays and the presence of too many faults. Moreover none of these localities is available now for field studies, due to the quarry development. The fossil bones were found close to each other, forming lens-like accumulations. They were cov- ered by a calcitic crust around their surface, which made them very difficult and time con- suming to prepare. The fossil fauna of Sésklo is already described in older studies (Symeonidis & Tataris 1983; Symeonidis 1992; Athanassiou 1996). The pres- ence of fossil bones in the sediments is also men- tioned by Müller (1983) and Mastoras (1985), who worked on the geology of the basin. The faunal list, given by Athanassiou (1996) (and, concerning the gazelles, revised by Kostopoulos & Athanassiou 1997), includes Carnivora (Nyctereutes megamastoides [Pomel, 1843], Vulpes cf. alopecoides Forsyth Major, 1875, Homo- therium crenatidens [Fabrini, 1890]), Proboscidea (Anancus arvernensis [Croizet & Jobert, 1828], Mammuthus meridionalis [Nesti, 1825]), Perissodactyla (Equus stenonis Cocchi, 1867, Stephanorhinus sp.) and Artiodactyla (cf. Croizetoceros ramosus [Croizet & Jobert, 1828], Athanassiou A. 440 GEODIVERSITAS • 2001 • 23 (3) THESSALY Sésklo FIG. 1. — Sketch map of the Thessalian area, showing the locality of Sésklo. Equus stenonis (Mammalia, Perissodactyla, Equidae) from Sésklo (Greece) 441 GEODIVERSITAS • 2001 • 23 (3) -11.000 +13.500 +13.000 +12.500 -10.500 -10.000 -9.500 FIG. 2. — Topographical map of the clay pit of Sésklo (dated April 17, 1981), where the several collections were carried out. The letters indicate the positions of the collection sites. cf. Eucladoceros sp., Macedonitherium martinii Sickenberg, 1967, Gazella borbonica Depéret, 1884, Gazella bouvrainae Kostopoulos, 1996, Gazella sp., Gazellospira torticornis [Aymard, 1854], as well as some unusual, mainly large sized forms, assigned to Caprini and Ovibovini). The faunal assemblage is of the so called “villafranchi- an type” and suggests a lower MN17 (MNQ17) age (Athanassiou 1996). The equid material is abundant, being the richest Equus stenonis sample among those that come from the already known localities of Greece. Plio-Pleistocene stenonid horses are known from several localities in Greece: Kos (Airaghi 1928; Desio 1931), Líbakos, Pol´ ylakkon, Aliákmon basin (Steensma 1988), Krímni, Gerakaroú, Ríza, Ravin of Voulgarákis (Koufos 1992), Dafneró (Koufos & Kostopoulos 1993) and Vólax (Koufos & Vlachou 1997). Some scanty equid materials are also probably referable to Equus stenonis: Paraskevaidis (1953) described some remains of a stenonid horse from Attica. Van der Meulen & Van Kolfschoten (1988) referred some equid remains from P´ yrgos to E. cf. stenonis and E. cf. stehlini Azzaroli, 1965. A horse with stenonid affinities, but probably of younger age, is also reported from Vaterá (Lésbos Island, Dermitzakis et al. 1991). A recent excavation in another site of this locality (Site F) yielded an interesting Plio-Pleistocene fauna that includes a large but slender stenonid horse (Eisenmann in press). The stenonid horses are the most common fossils in the European larger Mammal faunas of the villa- franchian type. Several local samples have been described until now, usually referred to as sub- species of Equus stenonis. Some well known of them are those from Saint-Vallier, Senèze, Chilhac and Venta Micena, which have been assigned to distinct subspecies, E. s. vireti Prat, 1964, E. s. senezensis Prat, 1964, E. s. guthi Boeuf, 1983 and E. s. granatensis Marin, 1987, respec- tively, while the samples from the sites in Valdarno and neighbouring localities (e.g., Olivola, Matassino) are usually referred to the nominal subspecies (De Giuli 1972). The com- mon practice of erecting subspecies based on local samples has been well-criticised by Groves (1986), and recently by Forsten (1998, 1999), since they have a point-like distribution in space and time and they may not represent geographi- cally isolated populations of the same species. However, the use of the subspecies category is still broadly accepted in the fossil horse studies. Recently, Caloi (1997) made the rather exagger- ated suggestion that every good E. stenonis samples should be distinguished from the others by a sub- specific name, stressing its particular palaeo- ecological adaptations. Some authors doubted the attribution of some of the above-mentioned samples to Equus stenonis, as this species name has been used collectively for most of the Plio-Pleistocene stenonid horses and, therefore, presents relatively high metrical and morphological variation. Caloi & Palombo (1987) and Forstén (1999) refer the Venta Micena horse to Equus altidens von Reichenau, 1915 or E. cf. altidens, while, according to a recent study by Eisenmann (1999), it should be given a full specific rank (Equus granatensis). Forsten (1999) tentatively groups the small and/or gracile forms of southern Europe (includ- ing the horse material from the Greek localities Líbakos, Krímni and Gerakaroú, previously attributed to E. stenonis mygdoniensis Koufos, 1992) under E. cf. stehlini or E. cf. altidens. The raised taxonomical problem is difficult to solve, as it is almost impossible to draw objective metri- cal boundaries between E. stehlini/altidens and E. stenonis. The discussion on the specific attribu- tion of the slender stenonid forms is beyond the scope of this study. To avoid any confusion, I will use the locality names instead of the several taxonomical names proposed, when comparing the available samples. MATERIAL AND METHODS The studied material comes from a single site (Site B in Fig. 2, excavation of the year 1982). The Site D (Fig. 2, excavation of the year 1991) also yielded an inadequate number of badly preserved equid remains (mainly a proximal and a distal tibia fragment) that do not differ either morpho- logically or metrically from those of the Site B. However, they have been excluded from the statis- tical sample, as they possibly come from a different level. The morphological and metrical compar- isons are based mainly on equid material from the collections of the Natural History Museum of Basel, Switzerland, and on bibliographical data. The studied specimens are described and meas- ured according to the suggestions of uploads/Litterature/ new-data-on-the-cocchi-1867-from-the-late-pliocene-locality-of-sesklo-thessaly-greece.pdf

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