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The North American land-mammal-age system was formalized in 1941 as a series of provincial land-mammal ages. [2] The system was the standard for correlations in the terrestrial Cenozoic record of North America and was the source for similar time scales dealing with other continents.
North American land mammal age This page was last edited on 12 August 2017, at 17:07 (UTC). Text is available under the Creative Commons Attribution-ShareAlike ...
In 1941, a committee chaired by Horace E. Wood II compiled a list of 19 "provincial ages" for North America, later called North American Land Mammal Ages (NMLAs). An example of an NMLA is the Rancholabrean, named after the Rancho La Brea fossil site. One of its characteristic fossils is the bison, which first appears in the Rancholabrean. [7]
The beginning of the Irvingtonian is defined by the first appearance of Mammuthus south of 55° N in North America, and the beginning of the succeeding Rancholabrean is defined by the first appearance of Bison. [4] In South America, it chronologically overlaps with the Uquian (partial), Ensenadan, and Lujanian in South American Land Mammal Ages.
The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 4,750,000 to 1,806,000 years BP, a period of 1] It is usually considered to start in the early-mid Pliocene Epoch and end by the early Pleistocene. [2]
The Rancholabrean North American Land Mammal Age on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), [1] Named after the famed Rancho La Brea fossil site (more commonly known as the La Brea tar pits) in Los Angeles, California, [2] the Rancholabrean is characterized by the presence of the genus Bison, which appeared ...
The Clarkforkian North American Stage, on the geologic timescale, is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 56,800,000 to 55,400,000 years BP lasting
The Orellan is a North American Land Mammal Age typically set from around 33,700,000 to 32,000,000 years BP, a period of 1] The Orellan is preceded by the Chadronian and followed by the Whitneyan NALMA stages.