Megacricetodon yei, Bi & Meng & Wu, 2008

Bi, Shundong, Meng, Jin & Wu, Wenyu, 2008, A new species of Megacricetodon (Cricetidae, Rodentia, Mammalia) from the Middle Miocene of northern Junggar Basin, China, American Museum Novitates 3602 (1), pp. 1-24 : 3

Megacricetodon yei , n. sp.

HOLOTYPE: IVPP V15349.1 , a fragmentary right maxilla with M1–M3 ( fig. 3 )

REFERRED MATERIAL: IVPP V 15349.2, a fragmentary right maxilla with M1–M3; V 15349.3, a right M1; V 15349.4, a right M2; V 15349.5-6, 2 right M3; V 15349.7, a left maxilla with M1–M3; V 15349.8, a left maxilla with M1–M3; V 15349.9, a left maxilla with the zygomatic plate and M1; V 15349.10–11, 2 left M2; V 15349.12–13, 2 left M2; V 15349.14–15, 2 left M3; V 15349.16–19, 4 right upper incisors; V 15349.20–22, 3 left upper incisors; V 15349.23, an almost complete left mandible except the broken angular process; V 15349.24, a left fragmentary mandible with the incisor and m1–3; V 15349.25, a left fragmentary mandible with m1–m3; V 15349.26, a left fragmentary mandible with the incisor and m1–m3; V 15349.27, a left fragmentary mandible with m1–m3; V 15349.28, a left fragmentary mandible with the incisor; V 15349.29, a left fragmentary mandible with the incisor and m1–m2; V 15349.30, a left fragmentary mandible with the incisor, m1, and m3; V 15349.31, a left fragmentary mandible with m2; V 15349.32, a left fragmentary mandible with m1–m2; V 15349.33-34, 2 left m1; V 15349.35, a left m2; V 15349.36–37, 2 isolated m3; V 15349.38, a right fragmentary mandible with the incisor and m1– m3; V 15349.39, a right fragmentary mandible with the incisor and m2; V 15349.40, a right fragmentary mandible with the incisor and m1– m3; V 15349.41, a right fragmentary mandible with m2–m3; V 15349.42, a right fragmentary mandible with m1–m2; V 15349.43, a right fragmentary mandible with m2–m3; V 15349.44,a right fragmentary mandible with m1–m2; V 15349.45–46, 2 right m3; V 15350.1, a baculum; V 15350.2–3, 2 almost complete right humeri except the broken proximal end; V 15350.4, a left humerus except broken proximal end; V 15350.5–6, 2 distal portions of left humeri; V 15350.7, proximal portion of a right ulna; V 15350.8–10, 3 proximal portions of left ulnae; V 15350.11–12, 2 distal left ulnar ends; V 15350.13, a complete right femur except the broken distal end; V 15350.14–17, 4 fragmentary right femurs; V 15350.18–19, 2 fragmentary left femurs. V 15350.20–21, 2 complete right tibiae except the broken proximal end; V 15350.22–23, 2 complete left tibiae except the broken proximal end; V 15350.24–26, 3 fragmentary left tibiae; V 15350.27, a right calcaneus.

LOCALITY AND AGE: Site XJ 98018 (46 ° 40.128 9 N, 88 ° 30.846 9 E) at the Tieersihabahe locality in the northern Junggar Basin of China. The first sand bed of the Halamagai Formation, early Middle Miocene.

ETYMOLOGY: The species name, yei , is in honor of our colleague, professor Jie Ye, for his contribution to the study of Cenozoic stratigraphy and mammals in northern Xinjiang and discovery of the locality.

REPOSITORY: The specimens are housed in the collections of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences , Beijing .

DIAGNOSIS: A Megacricetodon species of medium size, M1 with clearly split anterocone, presence of the labial spur of the anterolophule and the posterior spur of the paracone in some M1s, medium to long mesoloph in M1–2, frequent occurrences of the double protolophules in M2 of the collection, M2 metalophule transverse or posteriorly directed, m1 anteroconid simple, mesolophid of medium length in m1–2, and presence of the entepicondylar foramen in the humerus.

DIFFERENTIAL DIAGNOSIS: Differs from Megacricetodon (5 Aktaumys ) dzhungaricus in having slightly smaller size; better bifurcated M1 anterocone; shorter mesoloph in M1 and M2; fewer occurrences of the labial spur of the anterolophule in M1; fewer occurrences of double protolophule and metalophule in M2. Differs from any other known species of Megacricetodon in having the following combination of features: well-bifurcated M1 anterocone; presence of a labial spur of the anterolophule in many M1s, double protolophules in most M2s, the presence of the posterior spur of paracone, and long mesoloph in M1 and M2, and single m1 anteroconid.

Figures

Fig. 3. Occlusal (A), lingual (B), and labial (C) views of upper cheek teeth of Megacricetodon yei (IVPP V15349.1; holotype).