Table of Content

15 June 2016, Volume 54 Issue 2

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A synopsis of Paleocene stratigraphy and vertebrate paleontology in the Qianshan Basin, Anhui, China 

WANG Yuan-Qing, LI Chuan-Kui, LI Qian, LI Ding-Sheng　

2016, 54(2):  89-120. 

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The Mesozoic and Cenozoic redbeds in the Qianshan Basin comprise a set of monocline clastic rocks and are subdivided into the Late Cretaceous Gaohebu Formation, the Paleocene Wanghudun Formation (including the Lower, Middle, and Upper members) and Doumu Formation (including the Lower and Upper members). Continuous investigations in the Qianshan Basin since 1970 have resulted in discovery of a lot of vertebrate specimens. Up to date, 61 species (including 9 unnamed ones) in 45 genera of vertebrates, representing reptiles, birds and mammals, have been reported from the Paleocene of the Qianshan Basin. Among them, mammals are most diverse and have been classified into 46 species (7 unnamed) of 33 genera, representing 16 families in 10 orders. According to their stratigraphic occurrence, seven fossiliferous horizons can be recognized in the Qianshan Paleocene. Based on the evidence of mammalian biostratigraphy, the strata from the Lower Member through the lower part of the Upper Member of Wanghudun Formation could be roughly correlated to the Shanghu Formation of the Nanxiong Basin (Guangdong Province) and the Shizikou Formation of the Chijiang Basin (Jiangxi Province), corresponding to the Shanghuan Asian Land Mammal Age (ALMA). Both the upper part of the Upper Member of Wanghudun Formation and the Doumu Formation could be correlated to the Nongshan Formation of the Nanxiong Basin and the Chijiang Formation of the Chijiang Basin, corresponding to the Nongshanian ALMA. Paleomagnetic results from several Chinese Paleocene basins suggest that the Shanghuan is roughly correlative to the Puercan and Torrejonian North American Land Mammal Ages (NALMA), while the Nongshanian correlative to the early to middle Tiffanian (Ti1–4a). The Shanghuan and the Nongshanian are probably correlated to the Danian and the Selandian of the Global Geologic Time Scale. Therefore, all the fossil vertebrates collected in the Qianshan Basin are the Early and Middle Paleocene in age. 

A new mimotonidan Mina hui (Mammalia, Glires) from the Middle Paleocene of Qianshan, Anhui, China

LI Chuan-Kui, WANG Yuan-Qing, ZHANG Zhao-Qun, MAO Fang-Yuan, MENG Jin 

2016, 54(2):  121-136. 

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Here we report a new genus and species, Mina hui gen. etsp. nov., of basal Glires from the Middle Paleocene of Qianshan, Anhui, China. The new taxon is characterized by combination of the following characters: medium-sized mimotonidan; upper dental formula 2.0.3.3; dI2 transversely narrow and having smooth labial surface without longitudinal groove; M1 the largest cheek tooth and other cheek teeth decreasing in size considerably away from M1 so that the external margin of the upper cheek tooth row is distinctlyarched labially; lingual side of upper molars unilaterally hypsodont and bearing no hypostria; hypocone being slightly distolingual to protocone; presence of a mesostyle; upper incisor with double-layered enamel structure; posterior border of anterior root of zygoma situated lateral to M1–2 and infraorbital foramen positioned low. M. hui is one of the earliest known Glires, co-existing with Heomys and Mimotonain Qianshan geographically and Middle Paleocene (ca. 61 Ma) chronologically. We consider that the Mimotonida would include two families: the monotypic Mimotonidae that contains Mimotona and Mimolagidae that includes Mimolagus, Gomphos, Anatolimys, Minaand possibly Amar aleator. Among known mimotonidans, Mimotonaprobably represents a primitive “morphotype” as the ancestor of lagomorphs, whereas Mimolagidae includes a side branch diverged from the clade evolved toward lagomorphs. Future research may show that Mimolagidae is not a natural group, and may possibly submerge into Mimotonida, or involve more than one family-level clade. The occurrence of Heomys, Mimotona and Mina from Qianshan show that Glires had already diversified by the Middle Paleocene. 

The incisor enamel microstructure of Mina hui(Mammalia, Glires) and its implication for the taxonomy of basal Glires  

MAO Fang-Yuan, LI Chuan-Kui, WANG Yuan-Qing, LI Qian, MENG Jin 

2016, 54(2):  137-155. 

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The incisor enamel microstructure of Mina hui Li et al., 2016 from the upper Wanghudun Formation, Middle Paleogene of Qianshan, Anhui is described following the hierarchical system ranging from crystallites to Schmelzmuster. The enamel sample was taken from the upper incisor of the holotype. The enamel consists of a very thin prismless external layer, a relatively thick outer layer (PE) with radial enamel and an inner layer (PI) with multilayered Hunter-Schreger bands (HSB). The thickness of HSB is irregular and the inclination has a small angle; no transition zones between the HSB; prism cross sections are irregularly round; interprismatic matrix is very thick with crystallites in the PE running parallel to the prism long axes. These characters resemble pauciserial HSB in rodents.Ribbon-like prism seams and convergent crystallite discontinuities areconsistent in different portions of the enamel, which are interpreted as a primitive feature for Glires, or even placental mammals. Compared with known enamel structure of basal Glires, the enamel of Minastands for the earliest known evidence of double-layered enamel of the group. It indicates that the early evolution of Glires and placental mammals is complex and adds more details to the enamel microstructure of the earliest Glires.  

A revision of Anhuichelys Yeh, 1979, the earliest known stem Testudinidae (Testudines: Cryptodira) from the Paleocene of China

TONG Hai-Yan, LI Lu, LI Ding-Sheng, CHEN Li-Min, LI Tao, YU Shu-Hua, YU Guo-Sheng, CHENG Xiao-Qing, DI Ye-Li, Julien CLAUDE 

2016, 54(2):  156-179. 

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  Our systematic revision of Anhuichelys Yeh, 1979, based on abundant new material from the Paleocene of Qianshan Basin, Anhui Province, China provides evidences for its assignment to the stem Testudinidae. Anhuichelys contains three species in the Paleocene of Qianshan Basin: A. siaoshihensis Yeh, 1979 from the Early Paleocene of Wanghudun Formation, A. tsienshanensis Yeh, 1979 from both Wanghudun and Doumu formations and A. doumuensis sp. nov. from the Middle Paleocene Doumu Formation.A. xinzhouensis Chen, 1983 from the Paleocene of Xinzhou, Hubei Province is synonymized with A. tsienshanensis. Associated with a terrestrial vertebrate fauna, Anhuichelys is likely a land turtle and also the first testudinoid to develop the hinge on the shell.