Gashatan

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The Gashatan is a regional stage in the terrestrial palaeogene of East Asia in the history of the earth . The Gashatan is the second stage in the succession of land mammal faunas in East Asia and follows the Nongshanian . It is being replaced by the Bumbanian . The Gashatan is correlated with the upper Thanetium ( Paleocene , Paleogene) of the chronostratigraphic structure of the earth's history.

Naming and history

The stage was already suggested by Romer (1966), but not defined in more detail. It is named after the locality Gashato (Inner Mongolia) and the fauna of fossil land mammals found there.

Definition, correlation and absolute dating

The base of the stage is defined by the first onset of the species Tribosphenomys minutus ( Alagomyidae , Glires , mammals ). In addition, Hyaenodontidae ( Creodonta ), Coryphodontidae ( Pantodonta ), Dinocerata , Rodentiaformes , Carpolestidae and Nyctitheriidae are used . The representatives of the Mesonychidae (Mesonychia) and Pastoralodontidae increase significantly in body size.

The level is currently at the top of the global thanetian stage of the upper Paleocene correlated. Expressed in absolute numbers, it is the period from 57.3 to 56 Ma.

In North American Land Mammal Stratigraphy (NALMA), the Gashatan probably corresponds to the Cliffordian and the highest part of the Tiffanian . However, the correlation is still very uncertain. According to Wang et al. (2007) the Gashatan includes the Cliffordian and a significantly larger proportion of the Tiffanian (than in the Time Scale Creator correlation). The Gashatan is not broken down further.

supporting documents

Individual evidence

  1. ↑ Missiaen, Peter & T. Smith 2008: The Gashatan (late Paleocene) mammal fauna from Subeng, Inner Mongolia, China. Acta Palaeontologica Polonica, 53 (3): 357-378, Warsaw.
  2. ↑ a b The absolute values ​​of the Gashatan were determined using the Time Scale Creator 6.0 (October 2012) .

literature

  • Romer, AS 1966: Vertebrate Paleontology. 467 pp., University of Chicago Press, Chicago.
  • Wang Yuanqing, Meng Jin, Ni Xijun & Li Chuanku (2007): Major events of Paleogene mammal radiation in China. Geological Journal, 42: 415-430, doi : 10.1002 / gj.1083