Equus stenonis Cocchi, 1867

Athanassiou, Athanassios, 2001, New data on the Equus stenonis Cocchi, 1867 from the late Pliocene locality of Sésklo (Thessaly, Greece), Geodiversitas 23 (3), pp. 439-469 : 442-452

Equus stenonis Cocchi, 1867

MATERIAL EXAMINED. — Isolated teeth and fragmentary material are not given in the list. Cranium part with the M3 sin. (∑-104); cranium part (cranial roof, zygomaticum, nasals) (∑-246); cranium part with C sin., I2-I3 sin., I2-I3 dex., P2-M3 sin., P2-P4 dex. (∑-203); part of maxilla with M3 sin. (∑-71); maxilla with P2-M2 sin. (∑-170); maxilla with P2-M3 sin. (∑-194); maxilla with P2-M3 dex. (∑-199); ossa praemaxillaria (∑-299); maxilla with DM 1- PM 2 sin. (∑- 380); maxilla with DM 1- DM 4 dex. and DM 2- DM 4 sin. (∑-383); part of maxilla with C sin. (∑-404); maxilla with PM 3-M3 dex. (∑-946); ossa praemaxillaria (∑-947); part of maxilla with M3 dex. (∑-953); ossa praemaxilaria with I1-I3 dex., I1-I3 sin. and C sin. (∑-1028); maxilla with P3-M1 dex. (∑-1029); maxilla with M1-M2 sin. (∑-1203); part of maxilla with M3 sin. (∑-1207); maxilla with P3-M3 sin. (∑-1220); right mandibular ramus with dm4-m1 (∑-441); part of left mandibular ramus with dm3/4 (∑-951); mandibula with i1-i3, c, p2-m3 (∑-1026); left mandibular ramus with dm1-dm3 (∑-1027); right mandibular ramus with dm3-dm4 (∑-1130); left mandibular ramus with dm2-dm3 (∑-1226); atlas (∑-39, ∑-248, ∑-1304, ∑-1314, ∑-1324); atlas, epistropheus (∑-16, ∑-253); vertebrae cervicales (∑-102, ∑-251, ∑-949, ∑-1301, ∑-1303, ∑-1306, ∑-1310); part of scapula, proximal part of humerus sin. (∑-1237); proximal part of humerus sin. (∑-1236, ∑-1247); distal part of humerus sin. (∑-166, ∑-210, ∑-281, ∑-315, ∑-342); distal part of humerus dex. (∑-209, ∑-211, ∑-265, ∑-666, ∑-667, ∑-668, ∑-1031, ∑-1235); parts of humerus, radius and ulna sin. (∑-99, ∑-356); proximal part of radius sin. (∑ -352, ∑-672, ∑-1238, ∑-1241); proximal part of radius dex. (∑-333, ∑-671, ∑-673, ∑-1032); distal part of radius sin. (∑-86, ∑-373, ∑-375, ∑-376, ∑-663, ∑-665, ∑-930); distal part of radius dex. (∑-662, ∑-664, ∑-1240, ∑-376); distal part of radius, os capitatum, os trapezoideum dex. (∑-468); distal parts of radius and ulna, ossa carpi dex. of a juvenile individual (∑-477); os lunatum sin. (∑-621); ossa metacarpalia II, III, IV dex. (∑-87); proximal parts of ossa metacarpalia II, III, IV sin. (∑-336, ∑-578); proximal parts of ossa metacarpalia II, III, IV dex. (∑-206);

A B

A-E

C

ossa metacarpalia II, III sin. (∑-108, ∑-113); ossa metacarpalia III, IV sin. (∑-114); proximal parts of ossa metacarpalia II, III sin. (∑-125, ∑-128, ∑-143); proximal parts of ossa metacarpalia II, III dex. (∑-36, ∑-309, ∑-551); proximal parts of ossa metacarpalia III, IV sin. (∑-142, ∑-147); proximal part of os metacarpale III sin. (∑-69, ∑-127, ∑-137, ∑-138, ∑-329, ∑-409, ∑-588, ∑-1253, ∑-1254, ∑-1255); proximal part of os metacarpale III dex. (∑-64, ∑-140, ∑-310, ∑-579, ∑-964); distal part of os metacarpale III sin. (∑-118, ∑-119, ∑-121, ∑-122, ∑-123, ∑-124, ∑-130, ∑-164, ∑-317, ∑-1219); distal part of os metacarpale III dex. (∑-106, ∑-117, ∑-134, ∑-165, ∑-205, ∑-303, ∑-307, ∑-311, ∑-583, ∑-584, ∑-585); distal part of os metacarpale III (∑-120); distal part of os metacarpale III, phalanx proximalis, phalanx media, phalanx distalis sin. (∑-153); os sesamoideum phalangis proximalis (∑-624); phalanx proximalis sin. (∑-353); phalanx proximalis dex. (∑-88, ∑-1005); phalanx proximalis (∑-1003); distal part of phalanx proximalis (∑-622); phalanx media sin. (∑-204); phalanx media dex. (∑-89); phalanx media, phalanx distalis sin. (∑-979); phalanx media, phalanx distalis dex. (∑-180); phalanx distalis dex. (∑-604, ∑-634); os coxae dex. (∑-45, ∑-59, ∑-219, ∑-941, ∑-963, ∑-1336, ∑-1338, ∑-1344); os coxae sin. (∑-51, ∑-220, ∑-1050, ∑-1313, ∑-1330); proximal part of femur dex. (∑-231, ∑-351); distal part of femur sin. (∑-705); distal part of femur dex. (∑-212, ∑-374, ∑-1246); proximal part of tibia sin. (∑-234, ∑-1244, ∑-2016); distal part of tibia sin. (∑-61, ∑-223, ∑-264, ∑-332, ∑-334, ∑-360, ∑-361, ∑-378, ∑-381, ∑-650, ∑-653, ∑-654, ∑-655, ∑-657, ∑-659, ∑-660, ∑-661, ∑-1250, ∑-2012); distal part of tibia dex. (∑-52, ∑-237, ∑-282, ∑-316, ∑-348, ∑-349, ∑-362, ∑-606, ∑-651, ∑-652, ∑-656, ∑-658); distal part of tibia, astragalus sin. of a juvenile individual (∑-18); distal part of tibia, astragalus, calcaneum dex. of a juvenile individual (∑-345); distal part of tibia, astragalus, calcaneum, os naviculare, os cuboideum, os cuneiforme mediale, os cuneiforme laterale, ossa metatarsalia II, III, IV dex. (∑-363); distal part of tibia, astragalus, calcaneum, os naviculare, os cuboideum, os cuneiforme mediale, os cuneiforme laterale sin. (∑- 1251); astragalus, calcaneum, os naviculare, os cuboideum, os cuneiforme mediale, os cuneiforme laterale, proximal parts of the ossa metatarsalia II, III, IV sin. (∑-22); os naviculare, os cuboideum, os cuneiforme mediale, os cuneiforme laterale, ossa metatarsalia II, III, IV dex. (∑-107, ∑-115); astragalus, calcaneum, os naviculare, os cuboideum, os cuneiforme mediale, os cuneiforme laterale dex. (∑-625); astragalus sin. (∑-188, ∑-228, ∑-250, ∑-312, ∑-611, ∑-612, ∑-613, ∑-614, ∑-1034); astragalus dex. (∑-226, ∑-227, ∑-238, ∑-284, ∑-301, ∑-323, ∑-609, ∑-615, ∑-634, ∑-1030); astragalus, calcaneum sin. (∑-502, ∑-601); astragalus, calcaneum dex. (∑-608); calcaneum sin. (∑-57, ∑-294, ∑-377, ∑-504, ∑-505, ∑-600, ∑-610, ∑-617, ∑-1046); calcaneum dex. (∑-193, ∑-215, ∑-239, ∑-616, ∑-635); os naviculare sin. (∑-236, ∑-298, ∑-976); os naviculare, os cuboideum, os cuneiforme mediale, os cuneiforme laterale dex. (∑-240); os cuneiforme mediale sin. (∑-695); os cuneiforme laterale sin. (∑-977); os cuneiforme laterale dex. (∑-337); ossa metatarsalia II-IV sin. (∑-109); os metatarsale III sin. (∑-112, ∑-202); os metatarsale III dex. (∑-126, ∑-177, ∑-192); proximal parts of ossa metatarsalia II-IV sin. (∑-149, ∑-144, ∑-160); proximal parts of ossa metatarsalia II-IV dex. (∑-47); proximal parts of ossa metatarsalia III-IV dex. (∑-244); proximal part of os metatarsale III sin. (∑-65, ∑-141, ∑-218, ∑-225, ∑-267, ∑-283, ∑-314, ∑-577); proximal part of os metatarsale III dex. (∑-150, ∑-151, ∑-352, ∑-353, ∑-571, ∑-1252); distal part of os metatarsale III sin. (∑-116, ∑-129, ∑-136, ∑-187, ∑-201, ∑-308, ∑-581, ∑-582, ∑-586, ∑-1045, ∑-1218, ∑-1256); distal part of os metatarsale III dex. (∑-105, ∑-135, ∑-587, ∑-982); distal part of os metatarsale III (∑-983, ∑-1257); distal part of os metatarsale III, phalanx proximalis, phalanx media, phalanx distalis, ossa sesamoidea phalangis proximalis, sin. (∑-157); distal part of os metatarsale III, phalanx proximalis, phalanx media, dex. (∑-981); os sesamoideum phalangis proximalis (∑-182); phalanx proximalis sin. (∑-602, ∑-1042); proximal part of phalanx proximalis (∑-605, ∑-980, ∑-1043, ∑-1044, ∑-1262, ∑-1266, ∑-1280); phalanx proximalis, phalanx media dex. (∑-326); phalanx media sin. (∑-295, ∑-603); phalanx media, phalanx distalis dex. (∑-620); phalanx distalis sin. (∑-186, ∑-318, ∑-982); phalanx distalis dex. (∑-321, ∑-1263); phalanx distalis (∑-340, ∑-341, ∑-623, ∑-978). MATERIAL CONSERVATION. — The material listed above belongs to the collections of the Museum of Geology and Palaeontology, National and Kapodistrian University of Athens, Greece.

LOCALITY. — Sésklo (Magnesia, Thessaly, Greece).

AGE. — Late Pliocene (lower MN17).

DESCRIPTION

Skull

The cranial morphology is known from three fairly well-preserved parts of skulls. At least two of them belong to aged individuals. The general aspect is that of a very large, relatively flat and elongated skull ( Table 1; Fig. 3A ). Its total length, from the prosthion to the supraoccipital crest, is estimated to 65 cm (combined measurement on ∑-203 and ∑-246), being one of the largest horse skulls. The neurocranium is relatively small. The temporal lines are very low and blunt. The frontal is broad. The nasals form a wide groove along their fairly plicate suture. The praemaxillaries and the nasal notch are very long, extending backwards to the area above P3 (combined observation on the available specimens). The upper cranial profile is slightly concave at the nasal region, while it is convex at the frontal region (above the orbits) and above the distal end of the nasal notch. The zygomatical arch is directed distally slightly towards the sagittal plane (it is not parallel to it).

Mandible

The mandible material consists of five small mandibular parts that belong to juvenile individuals and an almost complete (it only lacks the ascending rami) and well-preserved mandible (∑-1026; already published by Symeonidis 1992: table I) of an adult individual. The latter has relatively big dimensions ( Table 2) and it is very robust, especially in the symphysis region. The muzzle region is laterally compressed.

Upper dentition

The studied material contains an adequate number of upper toothrows and isolated teeth of the permanent and deciduous dentition ( Table 3; Fig. 4 A-C). Specimens belonging to individuals of different ages, from relatively young to very aged, are available. The former are very hypsodont. The hypsodonty index (according to Eisenmann et al. 1988) for the almost unworn non-isolated teeth (premolars of the maxilla ∑-170) cannot be calculated, as the tooth length at the middle of the crown is not accurately measurable. However it can be estimated to 43-45 for the P3 and to 38 for the P4. The hypsodonty index for an isolated P2 is 80; for an M3 it is 48. The styles of the buccal side of both molars and premolars are narrow (especially the mesostyle); no groove is observed on them.

A

B

C

The enamel plication is simple ( Table 4; Fig. 7A, B ). More intense enamel plication is, though, observed in the almost unworn teeth. A pli caballin is always present and well-developed in the unworn and moderately worn teeth (stages of wear 1-3), while it is absent in some worn ones. Its length is much greater in the fresh teeth (stage of wear 1). The number of plications (counted according to Eisenmann et al. 1988) is given in the Table 4. The low mean total number of the fossette plications – four for the premolars and six for the molars – is typical for the species ( Eisenmann 1980).

The generally short protocone is triangular, with straight or slightly convex lingual border, in the almost unworn teeth (it is elongated in the fresh M3 of ∑-946, as well as in the fairly worn molars of the ∑-1220), but it becomes more elliptical to round in the very worn ones. It generally resembles the morphology of Type 3 of Eisenmann et al. (1988: fig. 6A) or that of Type 7 in some cases (molars of ∑-1220). The protocone index is generally lower of 40 (except for the M1 and M2 of the maxilla ∑-1220 and the M2 of ∑-170), a value that is considered by Gromova (1949a) as the upper limit for Equus stenonis . This is also the case for the mean values of the samples of Saint- Vallier, Senèze and La Puebla de Valverde, where, however, the maximal values reach as high as 48 ( Eisenmann 1980: tables 56-58). The index of M1 is always higher than that of P4. The hypoconal groove is well-developed in the premolars and the M2 except for the worn ones. Occasionally (∑-1029, ∑-1220) a hypoconal islet is formed instead. The postfossette is always closed.

The incisors are preserved in two specimens. One (∑-203, Fig. 3B ) belongs to a very old individual; all teeth, including the incisors, are almost totally worn out. On the contrary, the other (∑-1208) belongs to a very young one; the incisors and the preserved canine are only slightly worn. The enamel islets on the incisor occlusal surface are much developed. Their form is very simple, without any plication. The presence of a canine indicates a male individual.

The deciduous dentition is known from a complete maxilla (∑-383, Fig. 3C ) and several isolated molars (∑-1211-1215, plausibly belonging to the same individual) of the same morphology. The deciduous molars are easily recognised by their relatively elongated occlusal surface, the thinner enamel and their small height. They have big dimensions; DM2-DM4 length measures 118 mm in ∑-383, which is slightly larger than a specimen from Saint-Vallier (about 115 mm) figured by Viret (1954: pl. 29-3), as well as than the specimens from Senèze (103-105 mm; Basel collection) and Gerakaroú (103-114 mm; Koufos 1992). Concerning the enamel morphology, they do not differ from the permanent ones. The plications are few and the protocones short. A progressive lengthening of the protocone is observed from DM2 to DM4. The right DM1 is present in ∑-383, while the presence of the left one is indicated by its empty socket. This specimen bears the only indication for the presence of this tooth. The area in front of P2 is not preserved in most of the other available maxillae mentioned above, with the exception of some specimens that belong to aged individuals, which would not retain this tooth, if any, at that age. So the constant presence of the DM 1 in the horse sample from Sésklo cannot be confirmed.

Lower dentition

The existing lower dentition specimens are very few, compared to the rest of the equid material of the locality. The permanent dentition is only known from the complete mandible ∑-1026. There are also five deciduous dentition fragments. The permanent dentition belongs to a rather aged animal. The incisor occlusal surface is trapezoidal in shape (due to wear) and it lacks any enamel islets. There is no trace of a dm1. The cheek teeth morphology is clearly of stenonid type ( Fig. 7C ). The lobes of the double knot are almost parallel to the longitudinal axis of the tooth; their lingual border is always convex, as well as the labial borders of the protoconid and the hypoconid (except for the hypoconid of the p2, especially of the right one, which is almost straight). The ectoflexid is not very deep; it reaches the base of the isthmus in the molars and it is a little shorter in the premolars. One should mention the small difference between molars and premolars concerning its depth. The linguaflexid is small and pointed; it has the same morphology in all cheek teeth. There is a well-developed pli caballinid in all premolars, while it is absent or vestigial in molars. No protostylid is observed. The total length of the toothrow is 191 mm. The total length of the premolars and the molars is 102 mm and 89 mm respectively. The hypsodonty of the lower teeth is not well-known. An almost unworn m 1 in the juvenile mandible ∑-441 is 63 mm high, corresponding to a hypsodonty index of about 50 or lower. The lower cheek dimensions are given in Table 5.

The deciduous molars do not essentially differ in the enamel morphology compared to the permanent ones. However, the ectoflexid is much deep- er, penetrating the isthmus of the double knot (it reaches the linguaflexid in dm4). The deciduous molars are also more elongated ( Table 5). The total length of the deciduous toothrow (dm2- dm4) equals about 110-111 mm (combined measurement on the specimens ∑-1027 and ∑-1130 that presumably belong to the same individual), which is a little higher or comparable to the lengths measured in Senèze (102.5-110.5; Prat 1980) and Gerakaroú (108 mm; Koufos 1992) and a little lower than the lengths given by Viret (1954) for Saint-Vallier (111-116 mm). A pli caballinid and a protostylid are observed in all teeth. A dm1 of small size is present in one specimen. It is not known if this tooth was present in the rest of the juvenile mandibles, as the area in front of dm2 is not preserved in anyone of them.

Postcranial material

The postcranial skeleton is known from a great number of limb bones, as well as from several vertebrae and some rib fragments. The limb bones are very long.

The humerus and radius ( Tables 6; 7) are represented in the material by numerous parts (there is no complete bone). Their morphology is typically equid, showing no special anatomical charac-

1 7 8 9 13 14 15 31

, Sésklo, n = 1-4. Standard: Equus hemionus Pallas, 1775 , Eisenmann (1980).

ters. The proximal part of the humerus is hardly known, as it is represented by only three badly preserved specimens. The distal part has large dimensions that equal those measured on specimens from Saint-Vallier (Basel collection) and those given by Viret (1954: 146) and Prat (1980: table 24) for the same locality. The specimens from Vólax ( Koufos & Vlachou 1997) have also comparable dimensions (but somewhat more compressed trochlea). The specimens from Gerakaroú ( Koufos 1992) are distinctly smaller. The proximal and distal parts of the radius are almost equally represented in the material. Most of the specimens are very well-preserved; the proximal part of the ulna in natural position is also preserved on two of them; in one case it is fused to the radius.

The carpal bones are rather few: there are only three isolated bones, a magnum, a trapezoid (both belonging to the same individual) and a lunatum, as well as one complete carpus of a juvenile individual (∑-477). The DAP and DT of the proximal articular surface of the magnum measure 39.4 and about 47 mm respectively.

2 3 4 5 7 10 11 12 13 14

FIG. 9. — Logarithmic ratio diagram comparing the mandibular measurements of horse samples from Sésklo and other localities; — —, Saint-Vallier, n = 2-4, Viret (1954); — —, Senèze, n = 1-5, Basel collection; ——x, Gerakaroú, n = 1-10, Koufos (1992); —+—, Dafneró, n = 1-2, Koufos & Kostopoulos (1993); —◊—, Vólax, n = 1, Koufos & Vlachou (1997);, Sésklo, n = 1. Standard: sample from Valdarno, n = 1-7, Basel collection.

The same measures for the distal articulation are 35.3 and 45.0 mm. The trapezoid is broken and it cannot be measured. The lunatum is relatively small; its maximal height (measured on the anterior surface) is 28.2 mm and its maximal width (DT) on the proximal articular surface is 32.5 mm. Their dimensions and morphology are very similar to those of specimens from Saint-Vallier and Senèze (Basel collection).

The metacarpal III ( Table 8; Fig. 5F, K, L ) is one of the best-represented bones in the sample, making it statistically more interesting. There are 45 specimens of adult individuals, but only four of them are complete. Three more specimens are juvenile. They are relatively robust, although they are not generally so stout as the metacarpals from western European localities. The lateral metacarpals are fused to the third metacarpal in some specimens (six of the totally 23 proximal parts). The distal part has moderately developed keel and sharp supra-articular fossae, which is in accordance with the morphology of Equus stenonis ( Gromova 1949a; De Giuli 1972). The mean distal supra-articular breadth is slightly higher than the mean distal articular breadth. The morphology of the small articular facets for the carpals and the lateral metacarpals is very variable and the borders among them are often not very clear (dull). This indicates that the corresponding measurements (8 and 9) have no statistical importance, as they are considerably variable.

The femur ( Table 9) is the most uncommon long bone of the studied material. The tibia ( Table 10; Fig. 4D ) is on the contrary represented by numerous specimens, almost exclusively of the distal part of the bone (the fragile proximal part is anyway rare as a fossil). No complete femur or tibia is found in the material. Both bones present typical equid morphology.

The calcaneum and the astragalus ( Tables 11; 12; Fig. 5 A-E) are the most common tarsals; each is represented by 15-20 fairly well-preserved specimens. The calcaneum possesses a moderately developed epiphyse (caput). In general it is much less robust than the caballoid calcaneum.

The astragalus shows characters that have been considered diagnostic for Equus stenonis ( Gromova 1949a; Prat 1980) and clearly distinguish them from the typical caballoid morphology of the bone: a) the articulation for the calcaneum is accomplished by three surfaces, instead of four; b) the lateral keel of the trochlea is distally less developed; c) in all specimens the medial keel of the trochlea turns out distally to a tubercle that is rarely observed in the modern species; d) the tubercle at the proximal end of the medial keel of the trochlea is moderately developed; e) the articular surfaces for the navicular and the cuboid form a very high edge between them. De Giuli (1972) states that the characters of the articular surfaces are not diagnostic. However, all studied specimens show high morphological similarity. The general appearance of the bone is rather narrow. The maximal height is comparable to the maximal breadth (the mean ratio of these two measurements is 0.96, ranging from 0.91 to 1.05).

The rest of the tarsal bones are found mainly in articulation with the adjacent tarsals and metatarsals (∑-240, ∑-363, ∑-625 and ∑-1251). There are also some isolated ones. In one case (∑-240), the cuboid and the lateral cuneiform are fused together.

The metatarsals III ( Table 13; Figs 5 G-J; 6A) are morphologically similar to the metacarpals (they have long diaphyses, moderately developed keel, sharp supra-articular fossae), with some differences, such as the more circular cross section at their proximal part and the flexion of the distal part towards the rear (a major criterion for the discrimination of distal metapodial fragments). They are also absolutely longer; the ratio of the mean maximal height of the third metacarpal to that of the third metatarsal is 86.4%. The supraarticular tuberosities are well-developed; the distal supra-articular breadth is generally higher than the distal articular breadth. No fusion between the third and the lateral metatarsals is observed.

The proximal phalanges ( Table 14; Fig. 6B, C ) are characterised by the very sharp trigonum phalangis (the so-called “V-scar”), which is not very much developed towards the distal part of the bone. This has been considered as a primitive character that distinguishes the stenonid from the caballoid horses ( Sondaar 1968; De Giuli 1972; Forsten 1975); however, Forsten (pers. comm.) recently doubted this distinction. The anterior proximal phalanges are in general higher, stouter and they have more symmetrical proximal articulation. The posterior ones are laterally more concave, having larger proximal articulation and more slender shaft, while the distal supra-articular tuberosities have a higher position on the bone.

The medial phalanges ( Table 15; Fig. 6B, C ) are short and robust, especially the anterior ones. The posterior ones are longer and narrower distally, having a more trapezoid aspect. A metrical comparison to other known specimens does not show any significant differences in the total height. In the measurements of breadth the material from Sésklo is clearly smaller than Saint- Vallier but generally larger than Senèze.

A

B

FIG. 10. — Scatter-diagrams of premolar (A) and molar (B) occlusal length (x-coordinate) to protocone length (y-coordinate) of several horse samples;, Valdarno, Basel collection; ◊, Vólax, Koufos & Vlachou (1997); O, Sésklo. The numbered squares represent the measurement ranges from Saint-Vallier (1), Senèze (2), La Puebla de Valverde (3), Chilhac (4), Venta Micena (5), Líbakos & Gerakaroú (6) and Dafneró (7), according to Eisenmann (1980), Boeuf (1983, 1986), Marin (1987), Steensma (1988), Koufos (1992) and Koufos & Kostopoulos (1993), respectively.

The distal phalanges ( Table 16; Fig. 6B, C ) are rather wide, generally wider and more robust compared to other E. stenonis specimens, except for those from Saint-Vallier and Chilhac (also Senèze for the posterior ones). The posterior ones are narrower, more pointed anteriorly and generally smaller than the anterior ones.

The proximal, medial and distal phalanges were discriminated to anterior and posterior according to the criteria given by Prat (1957), Förster (1960), Eisenmann & De Giuli (1974) and Dive & Eisenmann (1991).

Figures

FIG. 3. — Equus stenonis from Sésklo; A, cranium part (∑-246), dorsal view; B, cranium part of a very aged individual (∑-203), ventral view; C, maxilla of a juvenile individual (∑-383), ventral view. Scale bars: 100 mm.

FIG. 4. — Equus stenonis Cocchi, 1867 from Sésklo; A, right maxilla (∑-199) with P2-M3; B, left maxilla (∑-170) with P2-M2; C, left maxilla (∑-1220) with P3-M3; D, right tibia (∑-282). Scale bars: 50 mm.

FIG. 7. — The occlusal surfaces of the Equus stenonis Cocchi, 1867 from Sésklo; A, the upper toothrow of a young individual (∑-170); B, the upper toothrow of an aged individual (∑-194); C, the lower toothrow of an adult individual (∑-1026). Scale bar: 50 mm.

FIG. 5. — Equus stenonis Cocchi, 1867 from Sésklo; A, left calcaneum (∑-294); B, left calcaneum (∑-1046); C, left calcaneum and astragalus (∑-601); D, left astragalus (∑-188); E, right astragalus (∑-615); F, proximal articulation of the right metacarpals II-IV (∑-206); G, proximal articulation of the right metatarsals III-IV (∑-244); H, right tarsals (navicular, cuboid and cuneiforms) and metatarsals II-IV of a juvenile individual (∑-107); I, left metatarsals II-IV (∑-109); J, right metatarsal III (∑-177); K, left metacarpals II-III (∑-113); L, left metacarpals III-IV (∑-114). Scale bars: 50 mm.

FIG. 6. — Equus stenonis Cocchi, 1867 from Sésklo; A, right tibia, calcaneum, astragalus, navicular, cuboid, cuneiforms and metatarsals II-IV (∑-363); B, left distal metacarpal part, proximal, medial and distal phalanges (∑-153); C, left posterior proximal (∑-602), medial (∑-295) and distal (∑-186) phalanges. Scale bar: 100 mm.