SPALACIDAE Gray, 1821

Sen, Sevket, 2016, Rodents, lagomorphs and insectivores, Geodiversitas 38 (2), pp. 299-314 : 302

Family SPALACIDAE Gray, 1821

Spalacidae gen. and sp. indet. ( Fig. 1F, G )

MATERIAL. — Left M2 (3.45 × 3.45), right m3 (2.72 × 2.56), two lower incisors of which the one almost complete (3.25 × 3.12) and one left upper incisor (3.41 × 3.02). These specimens are numbered as TUR 951 to 954, and the upper incisor KÇ 601.

DESCRIPTION AND COMPARISON

The M2 has occlusal outline square shaped, although the distal part is slightly narrower than the mesial part. In its present state of wear, the sinus and mesosinus are connected. The anterosinus is preserved as two enamel islands. The mesoloph is strong and thick, but it does not reach the labial border. The posterosinus is absent. In lingual view, the crown height is 4.04 mm and the sinus depth is 2.83 mm. In labial view, the crown height is much less (1.90 mm) indicating a strong unilateral hypsodonty, and the only sinus open is the mesosinus that extends on 0.75 mm along the crown height.

The m3 has an S-shaped occlusal pattern. A bulge on the mesiolabial angle seems to be a remnant of the labial anterolophid. The metaconid is a well-defined cusp that has a strong distolabial spur. The ridge between the protoconid and entoconid is strait. The maximum crown height on the labial side is 2.99 mm, and the sinusid depth is 2.29. On the lingual side the crown height is 1.93 mm at the metaconid, and the mesosinusid depth is 1.08 mm. Both teeth have roots broken.

The upper incisor is much thinner than the ones in the extant Spalax , and its anterior face bears two thin furrows in the enamel next to the lateral margin.

The lower incisor tapers mesially and has a chisel-shaped wear facet.The enamel of anterior face is smooth and slightly convex.

These teeth are, first of all, characterized by their larger size, larger than any named species of Spalacidae . The representatives of this family are known since the late Oligocene with Vetusspalax progressus De Bruijn, Markovic & Wessels, 2013 from the locality of Banovici in Bosnia Herzegovina, dated to 24 Ma. During the early Miocene the family is represented with the genera Debruijnia Ünay, 1996 and Heramys Klein Hofmeijer & De Bruijn, 1985 known in Turkey and Greece. These are all small-sized species with rather low-crowned and less lophodont molars, compared to the later representatives of the family. During the middle and late Miocene, the dominant genus is Sinapospalax Sarica & Sen, 2003 , which is known by six named species from Turkey ( Sarica & Sen 2003; Sen & Sarica 2011). It includes medium to large-sized species with rather high-crowned and semihypsodont molars. The molars are already lophodont without, however, loosing the cusp shape in an early stage of attrition. Their lophodonty increases when molars are worn to 1/3 of their depth. The lophodonty of molars is notably stronger in late Miocene-Pleistocene genera Pliospalax Kormos, 1932 and Spalax Guldenstaedt, 1770 . Even in rather young individuals the cusps of molars of those genera are not well defined, and a little attrition deletes any cusp appearance and includes them in strong lophs. In addition, the molars of these genera have lophs organized in a S-pattern that is typical for cheek teeth of the Pliospalax and Spalax species.

Based on these criteria, the specimens from Küçükçekmece fit best with the Sinapospalax species. Also, the presence of a free strong mesoloph, a parasinus which becomes a parafosset in early wear stages, and a mesially oblique sinus are characters that the M2 from Küçükçekmece shares with Sinapospalax . However, all species of this genus have much smaller molars ( Fig. 2 ), preventing inclusion of the Küçükçekmece material in any known species. Such large molars already have been found in three localities in Turkey. Sarica & Sen (2003) described a large m1 (3.58 × 3.07 mm) from Sinap Loc 12 (Central Anatolia, MN10) as “ Sinapospalax n. sp. ” [sic]. Ünay (1996) mentioned the presence of a spalacid M1 (4.45 × 4.30 mm) at Düzyayla 1 (Central Anatolia, MN11). The early Pliocene locality of Çalta in the same region yielded an unpublished m3 (3.79 × 3.53 mm) that is even larger than the m3 from Küçükçekmece. One can wonder if these large teeth belonged to a discrete large sized species or they indicate the presence of some gigantic individuals in some spalacid populations.

Figures

FIG. 1. — Byzantinia bayraktepensis from Küçükçekmece West, Turkey: A, M1 dext (MNHN.F.TRQ955); B, M2-3 sin (TRQ956); C, fragment of m1 dext (TRQ957); D, m2 dext (TRQ958); E, m2 sin (TRQ959). Spalacidae gen. and sp. indet. from Küçükçekmece: F, M2 sin (TRQ951); G, m3 sin (TRQ952). Scale bar: 1 mm.

FIG. 2. — Length/width scatter diagram of the second upper molar (M2) in different species of Sinapospalax (S.), Pliospalax (P.) and Spalax. Note that only one M2 is noted from the localities of Sinap Loc. 65, Amasya and Küçükçekmece. Modified from Sen & Sarica 2011: fig. 4.