Revised geochronology of the Casamayoran South American Land Mammal Age: Climatic and biotic implications
Isotopic age determinations (40Ar/39Ar) and associated magnetic polarity stratigraphy for Casamayoran age fauna at Gran Barranca (Chubut, Argentina) indicate that the Barrancan “subage” of the Casamayoran South American Land Mammal “Age” is late Eocene, 18 to 20 million years younger than hitherto s...
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ftpubmed:oai:pubmedcentral.nih.gov:23931 2023-05-15T14:04:40+02:00 Revised geochronology of the Casamayoran South American Land Mammal Age: Climatic and biotic implications Kay, Richard F. Madden, Richard H. Vucetich, M. Guiomar Carlini, Alfredo A. Mazzoni, Mario M. Re, Guillermo H. Heizler, Matthew Sandeman, Hamish 1999-11-09 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC23931 http://www.ncbi.nlm.nih.gov/pubmed/10557304 en eng The National Academy of Sciences http://www.ncbi.nlm.nih.gov/pmc/articles/PMC23931 http://www.ncbi.nlm.nih.gov/pubmed/10557304 Copyright © 1999, The National Academy of Sciences Biological Sciences Text 1999 ftpubmed 2013-08-29T07:10:35Z Isotopic age determinations (40Ar/39Ar) and associated magnetic polarity stratigraphy for Casamayoran age fauna at Gran Barranca (Chubut, Argentina) indicate that the Barrancan “subage” of the Casamayoran South American Land Mammal “Age” is late Eocene, 18 to 20 million years younger than hitherto supposed. Correlations of the radioisotopically dated magnetic polarity stratigraphy at Gran Barranca with the Cenozoic geomagnetic polarity time scale indicate that Barrancan faunal levels at the Gran Barranca date to within the magnetochronologic interval from 35.34 to 36.62 megannums (Ma) or 35.69 to 37.60 Ma. This age revision constrains the timing of an adaptive shift in mammalian herbivores toward hypsodonty. Specifically, the appearance of large numbers of hypsodont taxa in South America occurred sometime between 36 and 32 Ma (late Eocene–early Oligocene), at approximately the same time that other biotic and geologic evidence has suggested the Southern high latitudes experienced climatic cooling associated with Antarctic glaciation. Text Antarc* Antarctic PubMed Central (PMC) Antarctic Argentina Chubut ENVELOPE(-62.533,-62.533,-76.100,-76.100) |
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English |
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Biological Sciences |
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Biological Sciences Kay, Richard F. Madden, Richard H. Vucetich, M. Guiomar Carlini, Alfredo A. Mazzoni, Mario M. Re, Guillermo H. Heizler, Matthew Sandeman, Hamish Revised geochronology of the Casamayoran South American Land Mammal Age: Climatic and biotic implications |
topic_facet |
Biological Sciences |
description |
Isotopic age determinations (40Ar/39Ar) and associated magnetic polarity stratigraphy for Casamayoran age fauna at Gran Barranca (Chubut, Argentina) indicate that the Barrancan “subage” of the Casamayoran South American Land Mammal “Age” is late Eocene, 18 to 20 million years younger than hitherto supposed. Correlations of the radioisotopically dated magnetic polarity stratigraphy at Gran Barranca with the Cenozoic geomagnetic polarity time scale indicate that Barrancan faunal levels at the Gran Barranca date to within the magnetochronologic interval from 35.34 to 36.62 megannums (Ma) or 35.69 to 37.60 Ma. This age revision constrains the timing of an adaptive shift in mammalian herbivores toward hypsodonty. Specifically, the appearance of large numbers of hypsodont taxa in South America occurred sometime between 36 and 32 Ma (late Eocene–early Oligocene), at approximately the same time that other biotic and geologic evidence has suggested the Southern high latitudes experienced climatic cooling associated with Antarctic glaciation. |
format |
Text |
author |
Kay, Richard F. Madden, Richard H. Vucetich, M. Guiomar Carlini, Alfredo A. Mazzoni, Mario M. Re, Guillermo H. Heizler, Matthew Sandeman, Hamish |
author_facet |
Kay, Richard F. Madden, Richard H. Vucetich, M. Guiomar Carlini, Alfredo A. Mazzoni, Mario M. Re, Guillermo H. Heizler, Matthew Sandeman, Hamish |
author_sort |
Kay, Richard F. |
title |
Revised geochronology of the Casamayoran South American Land Mammal Age: Climatic and biotic implications |
title_short |
Revised geochronology of the Casamayoran South American Land Mammal Age: Climatic and biotic implications |
title_full |
Revised geochronology of the Casamayoran South American Land Mammal Age: Climatic and biotic implications |
title_fullStr |
Revised geochronology of the Casamayoran South American Land Mammal Age: Climatic and biotic implications |
title_full_unstemmed |
Revised geochronology of the Casamayoran South American Land Mammal Age: Climatic and biotic implications |
title_sort |
revised geochronology of the casamayoran south american land mammal age: climatic and biotic implications |
publisher |
The National Academy of Sciences |
publishDate |
1999 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC23931 http://www.ncbi.nlm.nih.gov/pubmed/10557304 |
long_lat |
ENVELOPE(-62.533,-62.533,-76.100,-76.100) |
geographic |
Antarctic Argentina Chubut |
geographic_facet |
Antarctic Argentina Chubut |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC23931 http://www.ncbi.nlm.nih.gov/pubmed/10557304 |
op_rights |
Copyright © 1999, The National Academy of Sciences |
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1766275887112650752 |