Ochotona ozansoyi Sen, 2003

Sen, Sevket, 2016, Rodents, lagomorphs and insectivores, Geodiversitas 38 (2), pp. 299-314 : 308-309

Ochotona ozansoyi Sen, 2003

( Fig. 6 )

TYPE LOCALITY. — Loc. 84 in the Sinap Formation, Yassiören village, Ankara, Turkey. MN10, c. 9.4 Ma.

MATERIAL. — Two left P2, Two left and two right upper cheek teeth, one left M2, a right mandible fragment bearing m1-m2 and the alveoli of p4 and m3, one right p3 and three lower cheek teeth, all numbered from MNHN.F.TRQ965 to TRQ976.

MEASUREMENTS. — See Table 2.

DESCRIPTION

All upper cheek teeth are labially curved. The enamel is thick on the mesial and lingual margins of the lophs but thin on their distal and in particular labial margins. The P2 is short and wide. Its unique anteroflexus is oblique distolabially. The following upper cheek teeth have occlusal pattern formed of two sub equal lophs separated by a deep and distally curved hypoflexus. The M2 has a strong distolingual spur.

The mandible is broken, missing its anterior part and most parts of the ramus. In lateral view, its height below m2 is 6.5 mm. There are one large foramen and several small foramina below m1 close to the ventral margin. The ramus is gently inclined distally. In medial view, the distal end of the incisor reaches the base of the p4 according to the hole it left on the body. The p3 has a triangular occlusal outline.The anteroconid is triangular and without any lateral or medial depression. It is connected to the posterior complex by a rather large enamel bridge. The paraflexid is short and oblique posteriorly, while the protoflexid is transverse. The hypoflexid is also transverse and does not reach the middle of the occlusal surface. The lower cheek teeth have a diamond-shaped anterior lophid and a triangular posterior lophid, both connected by cement infill. On the mandible, the alveolus of m3 is single and rounded.

DISCUSSION

The ochotonid remains from Küçükçekmece West can be attributed without doubt to the genus Ochotona because the P2 has a simple occlusal pattern with one flexus, M2 has a distolingual spur, and the p3 has a triangle-shaped anterocone and almost transverse protoflexid and paraflexid. The oldest species of Ochotona in Turkey, O. ozansoyi , has been reported from Loc. 84 and O. cf. ozansoyi from Inönü in the Sinap Formation. In this species, the P2 is identical in size and morphology to that of Küçükçekmece West, except that on the P2 from Loc. 84 the paraflexus is less deep, indicating an early stage of evolution. The other upper cheek teeth from Küçükçekmece West are identical both in size and morphology to that of Sinap Loc.8 and Inönü. For lower teeth, the general pattern of p3 is identical to that of O. ozansoyi , but its length is about 5% smaller than the largest p3 of O. ozansoyi ( Sen 2003) . As known, the length and width of p3 increase with attrition, and consequently such a difference should be considered as an intraspecific variation.

Late Miocene representative of Ochotona are poorly documented (see review in Sen 2003). The best known species Ochotona eximia Khomenko, 1914 from Taraklia in Moldova is clearly larger than the pika from Küçükçekmece ( Erbajeva 1988; Sen 2003). Erbajeva (2003) and Erbajeva et al. (2006) described several new species of Ochotona from late Miocene localities in China and Mongolia.Among these species, O. chowmincheni Erbajeva, Flynn, Li & Marcus, 2006 is larger and its p3 has a trefoil-shaped anteroconid. O. gudrunae Erbajeva, Flynn, Li & Marcus, 2006 and O. tedfordi Erbajeva, Flynn, Li & Marcus, 2006 are similar in size to the Küçükçekmece pika, but their p3 is different in having a round anteroconid in O. gudrunae , and deep and oblique flexids in O. tedfordi .

Ochotona antiqua Argyropulo & Pidoplichko, 1939 is a well-known species in eastern European Pliocene localities. Čermák & Rekovetz (2010) gave a complete account on its morphology and dispersal. Suata-Alpaslan (2009) described a new species, O. mediterranensis , from the early Pliocene (MN14) locality of Iğdeli in central Turkey, similar in size and tooth pattern to O. antiqua . Both species are smaller than the pika from Küçükçekmece, and the p3 has paraflexid and protoflexid deeper and directed obliquely. In summary, the specimens from Küçükçekmece fit better with O. ozansoyi than any other species of Ochotona .

Order EULIPOTYPHLA Waddell, Okada & Hasegawa, 1999 Family ERINACEIDAE Fischer von Waldheim, 1817

Figures

FIG. 6. — Ochotona ozansoyi Sen, 2003 from Küçükçekmece West: A, B, P2 sin; C, P4 or M1 sin; D, P4 or M1 dext; E, M2 sin; F, p3 dext; G, mandible dext in lateral view; H, m1, m2 and alveoli of m3 of the same mandible. Cheek teeth in occlusal view. Black areas, enamel; dotted areas, cement infill.