Biostratigraphy and diversity of Paleogene perissodactyls from the Erlian Basin of Inner Mongolia, China.

60 pages : illustrations (some color), maps ; 26 cm.Extant perissodactyls (horses, rhinos, and tapirs) comprise a small portion of living mammals, but fossil perissodactyls were more diverse and commonly dominated Paleogene faunas. Unfortunately, the taxonomy and distribution of some Chinese Paleogene perissodactyls remain controversial and unclear, hampering the correlation of Asian paleofaunas with paleofaunas from other continents. Here we clarify the temporal and spatial distribution of Paleogene perissodactyl species from the Erlian Basin based on published specimens, archives, and our recent fieldwork. The strata of the Erlian Basin range nearly continuously from the late Paleocene to the early Oligocene, and almost all Eocene Asian Land Mammal Ages (ALMA) are based on corresponding faunas from the Erlian Basin. We revise the most complete section of deposits at Erden Obo (=Urtyn Obo) that range in age from the late Paleocene to the early Oligocene in the Erlian Basin, and correlate it with other type formations/faunas in the basin based mainly on the perissodactyl biostratigraphy and lithostratigraphy. Furthermore, we discuss perissodactyl faunal components and their diversity from the early Eocene to the early Oligocene in the Erlian Basin, as well as the correlation between middle Eocene ALMAs and North American Land Mammal Ages based on perissodactyl fossils. The general decrease in perissodactyl diversity from the middle Eocene to the late Eocene can probably be attributed to a global climatic cooling trend and related environmental changes. The diversity of perissodactyls declined distinctly during the Eocene-Oligocene Transition, when global average temperatures dropped considerably

New ctenodactyloid rodents from the Erlian Basin, Nei Mongol, China, and the phylogenetic relationships of Eocene Asian ctenodactyloids /

no. 382

New stratigraphic data from the Erlian Basin : implications for the division, correlation, and definition of Paleogene lithological units in Nei Mongol (Inner Mongolia) /

no. 357

Paleogene stratigraphy, Inner Mongolia

31 p. : ill. (some col.), maps ; 26 cm.Includes bibliographical references (p. 22-24).Newly measured stratigraphic sections are reported for Paleogene rocks in the Nuhetingboerhe-Huheboerhe (Camp Margetts) area of Nei Mongol (Inner Mongolia), China. The composite sequence in this region is 82.4 m thick, encompassing three lithological units separated by important depositional hiatuses. In stratigraphic order, these rock units correspond to the Nomogen, Arshanto and Irdin Manha formations. The sequence contains faunas from four Asian land-mammal "ages", the Gashatan, Bumbanian, Arshantan, and Irdinmanhan, which together span the interval from late in the late Paleocene to early in the middle Eocene. Comparisons with localities and sections documented since the time of the Central Asiatic Expeditions (CAE) show that the so-called Houldjin gravels of the CAE from this area are mostly Irdin Manha Formation and that the "Irdin Manha beds" of the CAE belong to the Arshanto and/or Nomogen formations. These findings reveal that previous concepts of the Irdin Manha and Arshanto faunas from the Camp Margetts area probably include fossils of different ages, so that the corresponding Asian land-mammal "ages" based on these faunas are problematic and need systematic revision. The Nomogen, Arshanto, and Irdin Manha formations are redefined

Biostratigraphy and diversity of Paleogene perissodactyls from the Erlian Basin of Inner Mongolia, China

no. 391