Teleolophus medius Matthew & Granger, 1925

Averianov, Alexander O. & Godinot, Marc, 2005, Ceratomorphs (Mammalia, Perissodactyla) from the early Eocene Andarak 2 locality in Kyrgyzstan, Geodiversitas 27 (2), pp. 221-237 : 226-228

Teleolophus medius Matthew & Granger, 1925 ( Fig. 2 J-L)

Teleolophus medius Matthew & Granger, 1925: 3 , figs 4, 5. — Xu & Chiu 1962: 316, pl. 1, fig. 7. — Radinsky 1965: 218, fig. 12B. — Reshetov 1975: 39, fig. 14, pl. 1, fig. 7; 1979: 33, pl. 1, fig. 7. — Lucas et al. 1997: 242, fig. 7A.

Deperetella ferganica Belyaeva, 1962: 144 , fig. 1. — Reshetov 1979: 38, fig. 6-3.

Teleolophus medius ? – Radinsky 1965: 219, fig. 12A, pl. 3, fig. 1.

Teleolophus cf. Teleolophus medius – Radinsky 1965: 220, fig. 12C.

Teleolophus ? ferganicus – Radinsky 1965: 221.

Teleolophus beliajevi Biryukov, 1974: 78 , figs 1, 2. — Reshetov 1979: 37, fig. 6-2.

? Teleolophus magnus Reshetov, 1975: 39 , figs 15, 16, pl. 1, figs 5, 6.

? Teleolophus magnus ? – Reshetov 1979: 35, pl. 1, figs 5, 6.

REFERRED MATERIAL. — ZIN 35285, left P2; ZIN 32756, right p3 trigonid.

DESCRIPTION

There are no traces of cement on the teeth. P2 is a submolariform tooth. The crown is heavily worn, trapezoidal in outline, with an oblique anterior side. The parastyle and the paracone are prominent cusps, the former being somewhat smaller and lower. Posterior to the paracone the ectoloph is straight. The metacone is completely eliminated by wear; this indicates that it was smaller than the paracone. The preprotocrista is shorter than the prehypocrista and bent along the anterior margin of the crown. The prehypocrista goes to the ectoloph at an angle of about 45°. The hypocone was relatively large. The strong cingulum borders nearly all the crown, being most developed along the lingual side. It is interrupted around the metastyle and between the paracone and the metacone on the labial side. The tooth had two roots. The posterior one is more than two times larger than the anterior one, and lies under the postero-lingual part of the crown.

The p3 trigonid (ZIN 32756) bears a long paracristid which goes through a relatively large paraconid to the antero-lingual corner of the tooth. There is a short but distinct accessory crest running from the paraconid lingually and parallel to the paracristid ( Fig. 2K ). The trigonid basin is shallow and small, completely closed ventrally by the cingulid. The protocristid is oblique to the antero-posterior tooth axis and bent near the metaconid. There is a well developed cingulid on the preserved fragment, which is interrupted only under the metaconid.

Measurements

P2 (ZIN 35285): see Table 2. p 3 (ZIN 32756): TRW = 9.0.

DISCUSSION

The only previously described specimen of deperetellid from the Andarak fauna was an unworn upper premolar (PIN 1996-1) from the Andarak 1 site, that has been considered as a P2 ( Belyaeva 1962: fig. 1; Radinsky 1965: 221; Reshetov 1979: fig. 6-3). This tooth, the holotype of Deperetella ferganica Belyaeva, 1962 , appears to be generally very similar with ZIN 35285. It differs from the latter mostly by its larger size ( Table 2) and its complete labial cingulum. The size difference between PIN 1996-1 and ZIN 35285 cannot be attributed to sexual dimorphism, because they differ also in the presence of the labial cingulum. Thus we consider here ZIN 35285 as a P2 and PIN 1996-1 as a P3. Moreover, in PIN 1996-1 the metaloph is meeting the ectoloph at an almost right angle, which also suggests that this tooth is a P3 rather than a P2. Such an assignment precludes the attribution of this taxon to the genus Deperetella , because the latter has a fully molariform P3 with strong parallel protoloph and metaloph.

ZIN 32756 (right p3 trigonid) is considered here as belonging to a deperetellid because it has a long paracristid, a shallow trigonid basin and a strong cingulid. Most important, a paraconid accessory crest is present on ZIN 32756, a feature recently found to be diagnostic of Teleolophus ( Dashzeveg & Hooker 1997: 116) . This makes the attribution of the Andarak’s deperetellid to the latter genus quite reasonable.

We tentatively assign Andarak’s upper premolars to T. medius because they are closer in size to those of this species than to those of T. magnus Radinsky, 1965 ( Table 2). The latter species is known only from the holotype (maxilla with lower jaws from the “Ulan Gochu”, late Eocene of Inner Mongolia, China; Radinsky 1965) and referred teeth from the late Eocene (Ergilian) localities Khoer-Dzan and Dzhavkhalan-Ula in Mongolia ( Reshetov 1979). Both Teleolophus species differ mostly in size, T. magnus being about 35% larger ( Radinsky 1965). T. medius from the Eocene Schinzhaly locality in Kazakhstan is about 10% larger than the topotypic sample of the species from Inner Mongolia (L u c a s e t a l. 1 9 9 7). I n t h e m i d d l e E o c e n e Mongolian locality Khaychin Ula 2 together with T. medius of typical size were found remains of Teleolophus approximating in size T. magnus , which were subsequently attributed to T. magnus ( Reshetov 1975: 39) and to T. magnus? ( Reshetov 1979: 35) . This difference may be caused by sexual dimorphism, so the limits of interspecific variation for Teleolophus are still unknown. In size ZIN 32756 is closer to a p3 of T. medius from Irdin Manha (W = 7.6; Radinsky 1965) than to a p3 of T. magnus from Dzhavkhalan-Ula (W = 12.8; Reshetov 1979).

Teleolophus (?) shandongensis Chow & Qi, 1982 (? = Teleolophus sp. from the same locality), known from a few teeth from the Guanzhuang Formation in Shandong, China ( Chow & Qi 1982), could belong to the primitive deperetellid Irdinolophus Dashzeveg & Hooker, 1997 , which is known from the Irdin Manha and possibly the Kholboldzhi faunas ( Dashzeveg & Hooker 1997: 115). Teleolophus primarius Qi, 1987 from the Arshanto Formation in Inner Mongolia, China ( Qi 1987: fig. 41a, b) also could be attributable to Irdinolophus ( Dashzeveg & Hooker 1997: 116) . Teleolophus xiangshanensis Zong, Chen, Huang & Xu, 1996 is known by a dentary fragment with d4 and m1-2, and an isolated m2 ( Zong et al. 1996: fig. 2-3, pl. 32, fig. 3) from the middle-late Eocene of Xiangshan in the Hengduan Mountains, Qinghai-Tibetan Plateau, China. It is characterized by a relatively small size and low crowned molars and also could belong to Irdinolophus . A dentary fragment with m2-3 from the same locality ( Zong et al. 1996: pl. 32, fig. 3), referred to “ Diplolophodon similis ” Zdansky, 1930 , has a similar morphology but slightly larg- er molars, with a tiny hypoconulid on m3. It may also belong to Irdinolophus .

Figures

FIG. 2. — A-I, Eoletes tianshanicus n. sp.; J-L, Teleolophus medius Matthew & Granger, 1925; in labial (A, G), anterior (I, L) and occlusal (B-F, H, J, K) views; Andarak 2, Kyrgyzstan, Alay beds, Irdinmanhan; A, B, ZIN 32754, holotype, left maxillary fragment with P2-M2 and alveolus of P1; C, ZIN 34023, right M1 or 2; D, ZIN 35283, left M2; E, ZIN 35284, left M3; F, ZIN 32758, right m1 or 2; G, H, ZIN 35282, right maxillary fragment with P1; I, ZIN 32755, left astragalus; J, ZIN 35285, left P2; K, L, ZIN 32756, right p3 trigonid. Scale bar: 1 cm.