Litolophus gobiensis

Bai, Bin, Wang, Yuanqing & Meng, Jin, 2010, New Craniodental Materials of Litolophus gobiensis (Perissodactyla, ‘‘ Eomoropidae’ ’) from Inner Mongolia, China, and Phylogenetic Analyses of Eocene Chalicotheres, American Museum Novitates 3688, pp. 1-28 : 3-4

LITOLOPHUS GOBIENSIS (Colbert) , 1934

HOLOTYPE: AMNH 26645 . A crushed skull and a mandible, probably belonging to the same individual ( Colbert, 1934).

PARATYPES: AMNH 26644 , 26646–26649 , 26653–26659 . Skulls, mandibles, forefeet and hind feet found in a small quarry, 6 miles west of Camp Margetts , Inner Mongolia .

REFERRED SPECIMENS: IVPP V16139 , a relatively well-preserved skull with right P2– M3 and left C–M3; V16140 -1, a greater part of right side of a skull with P1–4 and M3; V16141 -1, a posterior portion of a skull with right P2–M1, M3 and left P2–4, M2–3; V16141 -2, a right side of the anterior portion of a skull; V16142 , a dorsoventrally compressed subadult skull with P2–M3; V16143 , a fragmentary premaxilla with I3; V16144.1, a right I2; V16144.2, a left I2; V16144.3, a left I2; V16144.4, a right I3; V16147 , a subadult mandible with right p3–m3 and left i1, p2–m3; V16148 , a partial subadult left lower mandible with p3–m3 and two i1s; V16149 , a nearly complete mandible with c–m3; V16150 , a nearly complete mandible with p2–m3; V16167.1, a right i2; V16167.2, a right i2; V16167.3, a right i2; V16167.4, a left i3; V16167.5, a left i3.

EMENDED DIAGNOSIS: Medium-sized chalicotheres with low-crowned teeth; dental formula 3? 1? 4? 3/3? 1? 3? 3; a short diastema present between P1 and P2; P3–4 metalophs joining the ectolophs in a low position, and paraconules usually well developed; upper molars with prominent parastyles and paraconules, but lacking mesostyles; paracones and metacones on upper molars nearly vertically implanted, protocones posteriorly extended, and metalophs oblique and relatively short; M3 metaloph and metacone posterobuccally rotated; lower molar cristid obliqua anterolingually directed to the buccal sides of the ‘‘metastylids,’’ and the hypolophids oblique; posterior cingulids on m1–2 raised upward but lacking the cuspate hypoconulids; m3 with a well-developed hypoconulid lobe; parietal crests gently contracted behind postorbital processes; supraorbital foramen absent; paroccipital process slender and completely separated from the relatively broader and larger posttympanic process; posterior border of the palate nearly U-shaped at the level of posterior edge of M3; ventral surface of the promontorium smooth; deep fossa for the stapedius muscle present; mandible long and slender, with long shallow symphysis and high ascending ramus; angular process of the mandible with a nearly semicircular border.

LOCALITY AND HORIZON: Nuhetingboerhe, Erlian Basin, Inner Mongolia, China. Lower part of the Arshanto Formation; early Arshantan (Early Eocene).