IVPP Loc. XJ200604 (Miocene of China)

Also known as Northwestern Junggar Basin, XJ 200604

Where: Xinjiang, China (46.7° N, 88.3° E: paleocoordinates 47.3° N, 87.7° E)

• coordinate based on nearby landmark

When: Shanwangian (16.9 - 13.7 Ma)

• Maridet et al. 2014: The discovery of Asianeomys aff. engesseri and Microdyromys aff. orientalis confirms an Early Miocene age for the locality. However, while Asianeomys engesseri is known from the Suosuoquan Formation Zone II, dated to between 21.7 and 21.9 Ma based on paleomagnetostratigraphic data (Meng et al. 2006), Microdyromys orientalis is known from the late Early Miocene Shanwangian locality of Sihong, thus possibly suggesting a younger age for XJ200604. Paleomagnetostratigraphic and isotopic dating suggest that the Shanwang and Sihong localities are about the same age (Deng 2006), with basalts underlying the Shanwang Formation having been dated to 18.05 ± 0.55 Ma (Cheng and Peng 1985). Keramidomys sp. and the new species of Ansomys from XJ200604 also resemble specimens from Sihong (Qiu 1987) and Gashunyin’adege in Inner Mongolia (Qiu Zhuding, personal communication 2011), thus cor− roborating a middle Shanwangian age for XJ 200604 (Fig. 2).

• bed-level stratigraphic resolution

Environment/lithology: fluvial; coarse-grained, pebbly sandstone

• The sediments exposed at this locality belong to an unnamed rock unit consisting of grayish− to blackish−yellow fluvial sandstone and sandy mudstone. Mammalian fossils were discovered in a lens of pebbly coarse sandstone in the basal layer of these fluvial sediments, which overlies the brightly−coloured Irtysh River Formation (Ye et al. 2005)

Size class: mesofossils

Reposited in the IVPP

Primary reference: X. Lu, X. Ni, L. Li and Q. Li. 2016. Two New Mylagaulid Rodents from the Early Miocene of China. PLoS ONE 11( e0159445):1-17 [P. Holroyd/P. Holroyd]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 197678: authorized by Patricia Holroyd, entered by Patricia Holroyd on 22.11.2018, edited by Grace Varnham

Creative Commons license: CC BY (attribution)

Taxonomic list

• The rich and diverse small mammal fauna discovered at this locality includes isolated teeth belonging to Gliridae, Eomyidae, Cricetidae, Aplodontidae, Sciuridae, Mylagaulidae, Erinaecidae and Soricidae, and Lagomorpha. A preliminary study of the small mammals identified two lagomorphs, three glirids (Miodyromys asiamediae Maridet, Wu, Ye, Ni, and Meng, 2011c, Microdyromys aff. orientalis Wu, 1986, and one unidentified species of Eliomys), four eomyids (Asianeomys aff. engesseri Wu, 1986, Asianeomys sp., Keramidomys sp., and an unidentified eomyid), three cricetids (Democricetodon sp., Cricetodon sp., and the new microtoid cricetid reported here), and a new species of Ansomys.
Mammalia
 Rodentia - Aplodontidae
Ansomys sp. Qiu 1987 mountain beaver
new species
 Rodentia - Eomyidae
Keramidomys sp., Asianeomys sp., "Asianeomys aff. engesseri" = Asianeomys dangheensis
Keramidomys sp. Hartenberger 1966 rodent
Asianeomys sp. Wu et al. 2006 rodent
"Asianeomys aff. engesseri" = Asianeomys dangheensis Wang 2002 rodent
 Rodentia - Cricetidae
Democricetodon sp. Fahlbusch 1964 mouse
Cricetodon sp. Lartet 1851 mouse
Primoprismus fejfari n. gen. n. sp. Maridet et al. 2014 mouse
Holotype: IVPP V18128, one left lower m2
 Rodentia - Gliridae
Eliomys sp. Wagner 1840 dormouse
 Rodentia - Mylagaulidae
Irtyshogaulus major n. sp. Lu et al. 2016 rodent
Irtyshogaulus minor n. gen. n. sp. Lu et al. 2016 rodent