Sharamynodon kirghisensis ( Belyaeva, 1971 )

Averianov, Alexander O. & Godinot, Marc, 2005, Ceratomorphs (Mammalia, Perissodactyla) from the early Eocene Andarak 2 locality in Kyrgyzstan, Geodiversitas 27 (2), pp. 221-237 : 233-234

Sharamynodon kirghisensis ( Belyaeva, 1971) ( Fig. 4 )

Lushiamynodon (?) kirghisensis Belyaeva, 1971: 40 , fig. 1.

Lushiamynodon ? kirghisiensis [sic] – Russell & Zhai 1987: 185.

Lushiamynodon ? sp. – Russell & Zhai 1987: 188.

Andarakodon kirghisiensis [sic] – Averianov & Potapova 1996: 1062, figs 1, 2A.

Sharamynodon kirghisensis – Lucas & Emry 2001: 522, fig. 5A.

REFERRED MATERIAL. — ZIN 34313, left and right maxillary fragments with P4-M3; ZIN 35299, left(?) upper(?) incisor; ZIN 34021, lingual part of left P3; ZIN 35300, left p4; ZIN 35301, left lower molar trigonid.

DESCRIPTION

For description and measurements of the upper cheek teeth see Belyaeva (1971: 40-42) and Averianov & Potapova (1996: 1062-1063).

The supposed upper incisor ( Fig. 4D, E ) is spatulate with a slightly asymmetrical crown and a heel-like cingulum projection.

The p4 is a molariform tooth with a relatively high (unilaterally hypsodont) crown somewhat compressed antero-posteriorly. The trigonid is only slightly smaller than the talonid. The protocristid and hypolophid are slightly oblique crests. The paracristid is very long. It markedly decreases in height toward the antero-lingual corner of the trigonid. Its anterior branch is nearly parallel to the protocristid. The metaconid is higher than the protoconid. The cristid obliqua is nearly perpendicular to the protocristid and joins it near its labial end. The hypoconid is higher than the entoconid, which is completely merged into the hypolophid. The narrow trigonid and talonid basins are open lingually. There are weak anterior and posterior cingulids, and there is a very weak and short labial cingulid between the bases of the protoconid and hypoconid. The tooth has two relatively small roots.

Measurements

ZIN 35300, p4: L = 14.2, WTR = 9.9, WTL = 10.6. ZIN 35301 (lower molar): WTR = 10.2.

DISCUSSION

T h e p4 Z I N 3 5 3 0 0 i s r e f e r r e d h e r e t o t h e Amynodontidae because of its relatively shortened and hypsodont crown, its very weak labial cingulid, and the entoconid not distinct from the hypolophid. By these characters this specimen differs from the p4s in the Asiatic Eocene hyracodontids Triplopus , Prohyracodon Koch, 1897 , Forstercooperia Wood, 1939 , and Juxia Chow & Chiu, 1964 (data from Radinsky 1967; Gabunia 1977; Lucas et al. 1981, 1997; Lucas & Sobus 1989; Dashzeveg 1991). It fits well in size with the teeth of S. kirghisensis ( Belyaeva 1971; Averianov & Potapova 1996) from the same locality. The WTL/L ratio in ZIN 35300 is 0.75, which is essentially the same as for the p4 of Z a i s a n a m y n o d o n b o r i s o v i f r o m K a z a k h s t a n ( Belyaeva 1971), or near this ratio in the Chinese specimens of Z. borisovi (0.62-0.68; Lucas et al. 1996).

Figures

FIG. 4. — Sharamynodon kirghisensis (Belyaeva, 1971); A-C, ZIN 35300, left p4; D, E, ZIN 35299, left(?) upper(?) incisor; in occlusal (A), lingual (B), labial (C), profile (D), and anterior (E) views; Andarak 2, Kyrgyzstan, Alay beds, Irdinmanhan. Scale bar: 1 cm.