Blancan
The Blancan North American Stage on the
As usually defined, it corresponds to the mid-
Dating issues
The start date of the Blancan has not been fully established. There is general agreement that it is between 4.9[3] and 4.3 mya (million years ago).[4] The often-cited GeoWhen database places it at 4.75 mya.[1]
There is even stronger disagreement about the end of the Blancan. Some stratigraphers argue for the 1.808 mya date that corresponds better with the end of the Pliocene and the start of the Pleistocene (1.808 mya). This conforms with the extinction of Borophagus, Hypolagus, Paenemarmota, Plesippus, Nannippus, and Rhynchotherium faunal assemblage between 2.2 and 1.8 mya.[2] Other paleontologists find continuity of the faunal assemblages well into the Pleistocene, and argue for an end date of 1.2 mya. This corresponds with the extinction of stegomastodons and related species and the appearance of mammoths in southern North America.[5]
Fauna
The middle of the Blancan, about 2.7 mya, is when the
Notable mammals
Carnivora – carnivores
Lagomorpha – lagomorphs
Perissodactyla – odd-toed ungulates
Rodentia – rodents
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Notable birds
Falconiformes – diurnal raptors
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See also
References
- ^ a b Blancan North American Stage. GeoWhen Database. Version 1.1.0. Retrieved 2017-June-26.
- ^ ISBN 0-520-05392-3
- S2CID 129779648.
- .
- .
- ISBN 1-56576-024-7
- ^ JSTOR 1363487.
- JSTOR 4083714.
Further reading
- Lourens, L. et al. (2004): The Neogene Period. In: Gradstein, F.; Ogg, J. & Smith, A.G. (eds.): A Geologic Time Scale 2004. Cambridge University Press. ISBN 0-521-78142-6
- Morgan, Gary S. & Lucas, Spencer G. (2003). "Mammalian Biochronology of Blancan and Irvingtonian (Pliocene and Early Pleistocene) Faunas from New Mexico" (PDF). Bulletin of the American Museum of Natural History. 279: 269–320. S2CID 87984338.