Quasi-static Eocene-Oligocene climate in Patagonia promotes slow faunal evolution and mid-Cenozoic global cooling
New local/regional climatic data were compared with floral and faunal records from central Patagonia to investigate how faunas evolve in the context of local and global climates. Oxygen isotope compositions of mammal fossils between c. 43 and 21 Ma suggest a nearly constant mean annual temperature o...
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ftunivlaplata:oai:sedici.unlp.edu.ar:10915/133449 2023-05-15T14:01:55+02:00 Quasi-static Eocene-Oligocene climate in Patagonia promotes slow faunal evolution and mid-Cenozoic global cooling Kohn, Matthew J. Strömberg, Caroline A. E. Madden, Richard H. Dunn, Regan E. Evans, Samantha L. Palacios, Alma Carlini, Alfredo Armando 2015 application/pdf 24-37 http://sedici.unlp.edu.ar/handle/10915/133449 en eng http://sedici.unlp.edu.ar/handle/10915/133449 issn:0031-0182 http://creativecommons.org/licenses/by-nc-sa/4.0/ Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) CC-BY-NC-SA Ciencias Naturales Hypsodonty Notoungulate Atmospheric CO2 Stable isotopes Precipitation Dust Articulo 2015 ftunivlaplata 2022-04-03T00:06:23Z New local/regional climatic data were compared with floral and faunal records from central Patagonia to investigate how faunas evolve in the context of local and global climates. Oxygen isotope compositions of mammal fossils between c. 43 and 21 Ma suggest a nearly constant mean annual temperature of 16 ± 3 °C, consistent with leaf physiognomic and sea surface studies that imply temperatures of 16–18 °C. Carbon isotopes in tooth enamel track atmospheric δ 13 C, but with a positive deviation at 27.2 Ma, and a strong negative deviation at 21 Ma. Combined with paleosol characteristics and reconstructed Leaf Area Indices (rLAIs), these trends suggest aridification from 45 Ma (c. 1200 mm/yr) to 43 Ma (c. 450 mm/yr), quasi-constant MAP until at least 31 Ma, and an increase to ~ 800 mm/yr by 21 Ma. Comparable MAP through most of the sequence is consistent with relatively constant floral compositions, rLAI, and leaf physiognomy. Abundance of palms reflects relatively dry-adapted lineages and greater drought tolerance under higher p CO2 . Pedogenic carbonate isotopes imply low p CO2 = 430 ± 300 ppmv at the initiation of the Eocene–Oligocene climatic transition. Arid conditions in Patagonia during the late Eocene through Oligocene provided dust to the Southern Ocean, enhancing productivity of silicifiers, drawdown of atmospheric CO 2 , and protracted global cooling. As the Antarctic Circumpolar Current formed and Earth cooled, wind speeds increased across Patagonia, providing more dust in a positive climate feedback. High tooth crowns (hypsodonty) and ever-growing teeth (hypselodonty) in notoungulates evolved slowly and progressively over 20 Ma after initiation of relatively dry environments through natural selection in response to dust ingestion. A Ratchet evolutionary model may explain protracted evolution of hypsodonty, in which small variations in climate or dust delivery in an otherwise static environment drive small morphological shifts that accumulate slowly over geologic time. Facultad de Ciencias Naturales y Museo Article in Journal/Newspaper Antarc* Antarctic Southern Ocean Universidad Nacional de La Plata (UNLP): SeDiCI (Servicio de Difusión de la Creación Intelectual) Antarctic Patagonia Southern Ocean The Antarctic |
institution |
Open Polar |
collection |
Universidad Nacional de La Plata (UNLP): SeDiCI (Servicio de Difusión de la Creación Intelectual) |
op_collection_id |
ftunivlaplata |
language |
English |
topic |
Ciencias Naturales Hypsodonty Notoungulate Atmospheric CO2 Stable isotopes Precipitation Dust |
spellingShingle |
Ciencias Naturales Hypsodonty Notoungulate Atmospheric CO2 Stable isotopes Precipitation Dust Kohn, Matthew J. Strömberg, Caroline A. E. Madden, Richard H. Dunn, Regan E. Evans, Samantha L. Palacios, Alma Carlini, Alfredo Armando Quasi-static Eocene-Oligocene climate in Patagonia promotes slow faunal evolution and mid-Cenozoic global cooling |
topic_facet |
Ciencias Naturales Hypsodonty Notoungulate Atmospheric CO2 Stable isotopes Precipitation Dust |
description |
New local/regional climatic data were compared with floral and faunal records from central Patagonia to investigate how faunas evolve in the context of local and global climates. Oxygen isotope compositions of mammal fossils between c. 43 and 21 Ma suggest a nearly constant mean annual temperature of 16 ± 3 °C, consistent with leaf physiognomic and sea surface studies that imply temperatures of 16–18 °C. Carbon isotopes in tooth enamel track atmospheric δ 13 C, but with a positive deviation at 27.2 Ma, and a strong negative deviation at 21 Ma. Combined with paleosol characteristics and reconstructed Leaf Area Indices (rLAIs), these trends suggest aridification from 45 Ma (c. 1200 mm/yr) to 43 Ma (c. 450 mm/yr), quasi-constant MAP until at least 31 Ma, and an increase to ~ 800 mm/yr by 21 Ma. Comparable MAP through most of the sequence is consistent with relatively constant floral compositions, rLAI, and leaf physiognomy. Abundance of palms reflects relatively dry-adapted lineages and greater drought tolerance under higher p CO2 . Pedogenic carbonate isotopes imply low p CO2 = 430 ± 300 ppmv at the initiation of the Eocene–Oligocene climatic transition. Arid conditions in Patagonia during the late Eocene through Oligocene provided dust to the Southern Ocean, enhancing productivity of silicifiers, drawdown of atmospheric CO 2 , and protracted global cooling. As the Antarctic Circumpolar Current formed and Earth cooled, wind speeds increased across Patagonia, providing more dust in a positive climate feedback. High tooth crowns (hypsodonty) and ever-growing teeth (hypselodonty) in notoungulates evolved slowly and progressively over 20 Ma after initiation of relatively dry environments through natural selection in response to dust ingestion. A Ratchet evolutionary model may explain protracted evolution of hypsodonty, in which small variations in climate or dust delivery in an otherwise static environment drive small morphological shifts that accumulate slowly over geologic time. Facultad de Ciencias Naturales y Museo |
format |
Article in Journal/Newspaper |
author |
Kohn, Matthew J. Strömberg, Caroline A. E. Madden, Richard H. Dunn, Regan E. Evans, Samantha L. Palacios, Alma Carlini, Alfredo Armando |
author_facet |
Kohn, Matthew J. Strömberg, Caroline A. E. Madden, Richard H. Dunn, Regan E. Evans, Samantha L. Palacios, Alma Carlini, Alfredo Armando |
author_sort |
Kohn, Matthew J. |
title |
Quasi-static Eocene-Oligocene climate in Patagonia promotes slow faunal evolution and mid-Cenozoic global cooling |
title_short |
Quasi-static Eocene-Oligocene climate in Patagonia promotes slow faunal evolution and mid-Cenozoic global cooling |
title_full |
Quasi-static Eocene-Oligocene climate in Patagonia promotes slow faunal evolution and mid-Cenozoic global cooling |
title_fullStr |
Quasi-static Eocene-Oligocene climate in Patagonia promotes slow faunal evolution and mid-Cenozoic global cooling |
title_full_unstemmed |
Quasi-static Eocene-Oligocene climate in Patagonia promotes slow faunal evolution and mid-Cenozoic global cooling |
title_sort |
quasi-static eocene-oligocene climate in patagonia promotes slow faunal evolution and mid-cenozoic global cooling |
publishDate |
2015 |
url |
http://sedici.unlp.edu.ar/handle/10915/133449 |
geographic |
Antarctic Patagonia Southern Ocean The Antarctic |
geographic_facet |
Antarctic Patagonia Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
http://sedici.unlp.edu.ar/handle/10915/133449 issn:0031-0182 |
op_rights |
http://creativecommons.org/licenses/by-nc-sa/4.0/ Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) |
op_rightsnorm |
CC-BY-NC-SA |
_version_ |
1766271991341383680 |