Hipparion aff. giganteum Gromova, 1952 LOCALITY. — Küçükçekmece, Turkey. AGE. — Late Vallesian, MN 10; Late Miocene. MATERIAL. — See Table 1. MEASUREMENTS. — See Table 1. DESCRIPTION Upper cheek teeth The upper cheek teeth are large with very rich enamel plication in the fossette’s borders and with thin and very deep plis (Fig. 5); the plication number ranges between 14-31 in the premolars and between 23-24 in the molars. The protocone is large, elliptical-oval with flattened lingual wall in the less worn teeth; in MNHN.F.TRQ110 it bears a small mesial spur. The pli caballin is simple to triple. The distal hypoconal groove is well developed and deep while a large lingual hypoconal groove is present in the premolars and a small one in the molars. The P2 TRQ106 has a small and pointed anterostyle, closed fossettes, very rich enamel plication in the fossette’s borders (mean plication number = 21), isolated and oval protocone with a small mesial spur, triple pli caballin, deep and narrow distal hypoconal groove, and a shallow and clear lingual hypoconal groove (Fig. 5). The presence of the lingual hypoconal groove, the very rich enamel plication, the multiple pli caballin, and the size of the P2TRQ106 fit well with the Küçükçekmece form-B morphology. Lower cheek teeth The lower premolars are unworn or less worn preventing the description of their occlusal morphology (Fig.5). However, the lower molars (MNHN.F.TRQ46, TRQ111) are more worn and their morphology is clear. The parastylid is well developed and high in TRQ46. The ectoflexid is narrow and deep in the molars with a weak pli caballinid, and the linguaflexid is deep and V-shaped. The pli caballinid is weak and it is reduced by the wear. The metaconid and metastylid are rounded (in the less worn teeth they are elliptical) and the entoconid squarish. The preflexid and postflexid borders are plicated and (or) crenulated. There is not any trace of the ectostylid. Metapodials There is only a fragment of the McIII and an almost complete MtIII (Fig. 6). The slenderness index is 17 for the MtIII and the keel index is 117 for the McIII and 118 for the MtIII, indicating short and robust metapodials with weak keel.

Published as part of Koufos, George D. & Sen, Sevket, 2016, Equidae, pp. 225-243 in Geodiversitas 38 (2) on page 232, DOI: 10.5252/g2016n2a5, http://zenodo.org/record/4535533