Ordosemys Brinkman and Peng, 1993a

TONG, HAIYAN, JI, SHU-AN & JI, QIANG, 2004, Ordosemys (Testudines: Cryptodira) from the Yixian Formation of Liaoning Province, Northeastern China: New Specimens and Systematic Revision, American Museum Novitates 3438 (1), pp. 1-20 : 2-3

Ordosemys Brinkman and Peng, 1993a

DIAGNOSIS (modified from Brinkman and Peng, 1993a): A cryptodire with a low domed shell and plastron loosely connected to the carapace as in macrobaenids, differing from all other macrobaenids in having a shell that is nearly as wide as long, in the presence of a preneural and in the presence of a medial fontanelle between the hypoplastron and xiphiplastron; differering from Macrobaena Tatarinov, 1959 , Anatolemys Khozatskii and Nesov, 1979 , Hangaiemys Sukhanov and Narmandakh, 1974 , and Kirgizemys Nesov and Khozatskii, 1973 in that the vertebral scutes are wider than they are long; differering from Sinemys Wiman, 1930 and Manchurochelys Endo and Shikama, 1942 in having the posterior lobe of the plastron wider at the basis. Skull similar to Macrobaena and differing from Hangaiemys and Dracochelys Gaffney and Ye, 1992 in having a wider triturating surface; canalis caroticus internus unfloored or with a thin floor, the foramina anterior canalis caroticus interni located close together at the base of the sella turcica, with sella turcica reduced in size, not reaching the dorsum sellae.

TYPE SPECIES: Ordosemys leios Brinkman and Peng, 1993a .

Ordosemys liaoxiensis ( Ji, 1995)

Figures 1–9

REFERRED SPECIMENS: GM V3001, a nearly complete skeleton visible in ventral view (figs. 1, 2, 8, 9); GM V3002, a nearly complete shell and associated skull and limb bones visible in dorsal view (fig. 7); GM V3000­1, an incomplete skeleton in which a half carapace and plastron, skull, neck, and right forearm are preserved; GM V3000­2, a skeleton with skull, neck, carapace and plastron, part of tail and some limb bones (figs. 5, 6); GM V3000­3, a skull and partial neck visible in ventral view; GM V3000­4, a skull and partial neck (figs. 3, 4).

LOCALITY AND HORIZON: Yixian Formation, Liaoning Province, northeastern China.

DIAGNOSIS (modified from Ji, 1995, Li and Liu, 1999): A species of Ordosemys , differing from O. leios in having a slight ornamentation on the shell surface, a large semicircular lateral fontanelle on the bridge, and in having the first peripheral not contacting or barely contacting the first costal plate.

MEASUREMENTS: See tables 1 and 2.

Figures

Fig. 1. Ordosemys liaoxiensis (Ji, 1995), GM V3001, Yixian Formation, Liaoning, China. Skeleton in ventral view. Scale bar = 50 mm.

Fig. 2. Ordosemys liaoxiensis (Ji, 1995), GM V3001, Yixian Formation, Liaoning, China. Skull in ventral view. Scale bar = 50 mm.

Fig. 3. Ordosemys liaoxiensis (Ji, 1995), GM V3000­4, Yixian Formation, Liaoning, China. Skull in dorsal (A), ventral (B) and right lateral (C) views. Scale bar = 50 mm.

Fig. 4. Ordosemys liaoxiensis (Ji, 1995), GM V3000­4, Yixian Formation, Liaoning, China. Skull in dorsal (A), ventral (B) and right lateral (C) views. Key for figure 3.

Fig. 5. Ordosemys liaoxiensis (Ji, 1995), GM V3000­1 and GM V3000­2, Yixian Formation, Liaoning, China. Shell in dorsal (A) and ventral (B) views. Scale bar = 50 mm.

Fig. 6. Ordosemys liaoxiensis (Ji, 1995), GM V3000­1 and GM V3000­2, Yixian Formation, Liaoning, China. Shell in dorsal (A) and ventral (B) views. Key for figure 5.

Fig. 7. Ordosemys liaoxiensis (Ji, 1995), GM V3002, Yixian Formation, Liaoning, China. Shell in dorsal view. Scale bar = 50 mm.

Fig. 8. Ordosemys liaoxiensis (Ji, 1995), GM V3001, Yixian Formation, Liaoning, China. Detail of tail. Scale bar = 50 mm.

Fig. 9. Ordosemys liaoxiensis (Ji, 1995), GM V3001, Yixian Formation, Liaoning, China. Detail of forelimb. Scale bar = 50 mm. Abbreviations: dc, distal central; int, intermedium; mc, metacarpal; med cent, medial central; p, phalanx; pis, pisiform; uln, ulnare.