The Irvingtonian 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), spanning from 1.8 million – 250,000 years BP.[1][2] Named after an assemblage of fossils from the Irvington District of Fremont, California,[3] the Irvingtonian is usually considered to overlap the Lower Pleistocene and Middle Pleistocene epochs. The Irvingtonian is preceded by the Blancan and followed by the Rancholabrean NALMA stages.
The Irvingtonian can be further divided into substages:
- Irvingtonian I - approximately 1.9 MA TO 0.85 MA
- Irvingtonian II - approximately 0.85 MA TO 0.4 MA
- Irvingtonian III - approximately 0.4 MA TO 0.25 MA[1]
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.
- ^ a b The _Blancan, Irvingtonian and Rancholabrean Mammal Ages by Christopher J. Bell and Ernest L. Lundelius Jr., Anthony D. Barnosky, Russell W. Graham, Everett H. Lindsay, Dennis R. Ruez Jr., Holmes A. Semken Jr., S. David Webb, and Richard J. Zakrzewski. January 2004 in the book: Late Cretaceous and Cenozoic Mammals of North America: Biostratigraphy and Geochronology. Chapter: 7. Publisher: Columbia University Press; Editors: Michael O. Woodburne. pp274-276
- ^ Smith, Gregory James; DeSantis, Larisa R. G. (February 2020). "Extinction of North American Cuvieronius (Mammalia: Proboscidea: Gomphotheriidae) driven by dietary resource competition with sympatric mammoths and mastodons". Paleobiology. 46 (1): 41–57. doi:10.1017/pab.2020.7. ISSN 0094-8373.
- ^ Savage, D.E. (1951) Late Cenozoic vertebrates of the San Francisco Bay region, University of California Publications, Bulletin of the Department of Geological Sciences 28:215-314
- ^ "Irvingtonian North American Land Mammal Age". Florida Museum. 2017-03-28. Retrieved 2020-04-24.