Paracolodon fissus (Matthew and Granger, 1925)

Bai, Bin, Wang, Yuan-Qing, Mao, Fang-Yuan & Meng, Jin, 2017, New material of Eocene Helaletidae (Perissodactyla, Tapiroidea) from the Irdin Manha Formation of the Erlian Basin, Inner Mongolia, China and comments on Related Localities of the Huheboerhe Area, American Museum Novitates 2017 (3878), pp. 1-44 : 5-7

Paracolodon fissus (Matthew and Granger, 1925)

Desmatotherium fissum Matthew and Granger, 1925b: 3 , fig. 3.

Helaletes fissus Radinsky, 1965b: 230 , fig. 18.

Helaletes fissus Qi, 1987: 39 , fig. 28.

Colodon fissus Dashzeveg and Hooker, 1997: 112 .

HOLOTYPE: AMNH FM 20161 : left maxilla with P2–4.

REFERRED SPECIMENS: AMNH FM 81802: a left mandible with c–m3. AMNH FM 81804: a left mandible with p4–m3.

NEW MATERIAL: IVPP V 22640 : an associated cranium and mandible lacking rostral portion; IVPP V 23366.1, a left maxilla with P2–3 and root of P1; and IVPP V 23366.2, an isolated right M3.

LOCALITY AND HORIZON: Duheminboerhe (Camp Margetts) (IVPP V 22640 , V 23366.1), and Daoteyin Obo (IVPP V 23366.2), Erlian Basin, Inner Mongolia; Irdin Manha Formation, middle Eocene.

DIAGNOSIS: Preorbital portion relatively shorter compared with postorbital part. The lateral trough on ascending process of the maxilla extending posteriorly above the supraorbital process of the frontal. A pair of medial troughs on the dorsal surface of the frontal separated by a median anterior sagittal crest and extending posteriorly to the frontal line. P3–4 metaloph extending toward protocone, bypassing the hypocone. Posterior end of mandibular symphysis ending at the level of p2. p2–m3 relatively long and narrow. p3–4 entoconid small and distinct, talonid slightly wider than trigonid. m3 hypoconulid highly reduced.

DIFFERENTIAL DIAGNOSIS: Differs from Desmatotherium mongoliense in having an infraorbital foramen opening above the posterior border of P3, a symphysis of the mandible terminating at the level of p2, P2–4 more molariform, metaloph more prominent and extending toward the protocone, paracone and metacone more convex buccally, M1–2 metacone slightly shorter, M2 paracone vertically situated and more trapezoid in outline, M3 metacone less lingually depressed, p2–4 entoconid smaller, p4 talonid nearly as wide as trigonid, m3 hypoconulid highly reduced. Differs from Paracolodon inceptus in being smaller, and in having P3–4 more molariform, P2–4 paracone and metacone more closely situated, M1–2 metacone relatively longer, distobuccal cingulum lower, and M3 metacone less lingually depressed.