Seasonal variability in Arctic temperatures during early Eocene time

Jaelyn J. Eberle; Henry C. Fricke; John D. Humphrey; Logan Hackett; Michael G. Newbrey; J. Howard Hutchison

doi:10.1016/j.epsl.2010.06.005

Seasonal variability in Arctic temperatures during early Eocene time

Jaelyn J. Eberle^*, Henry C. Fricke, John D. Humphrey, Logan Hackett, Michael G. Newbrey, J. Howard Hutchison

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

74 Scopus citations

Abstract

As a deep time analog for today's rapidly warming Arctic region, early Eocene (52-53. Ma) rock on Ellesmere Island in Canada's High Arctic (~79°N.) preserves evidence of lush swamp forests inhabited by turtles, alligators, primates, tapirs, and hippo-like Coryphodon. Although the rich flora and fauna of the early Eocene Arctic imply warmer, wetter conditions than at present, the quantification of Eocene Arctic climate has been more elusive. By analyzing oxygen isotope ratios of biogenic phosphate from mammal, fish, and turtle fossils from a single locality on central Ellesmere Island, we infer early Eocene Arctic temperatures, including mean annual temperature (MAT) of ~8 °C, mean annual range in temperature of ~16.5-19 °C, warm month mean temperature of 19-20 °C, and cold month mean temperature of 0-3.5 °C. Our seasonal range in temperature is similar to the range in estimated MAT obtained using different proxies. In particular, relatively high estimates of early Eocene Arctic MAT and SST by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in terrestrial soil bacteria and isoprenoid tetraether lipids in marine Crenarchaeota fall close to our warm month temperature, suggesting a bias towards summer values. From a paleontologic perspective, our temperature estimates verify that alligators and tortoises, by way of nearest living relative-based climatic inference, are viable paleoclimate proxies for mild, above-freezing year-round temperatures. Although for both of these reptilian groups, past temperature tolerances probably were greater than in living descendants.

Original language	English
Pages (from-to)	481-486
Number of pages	6
Journal	Earth and Planetary Science Letters
Volume	296
Issue number	3-4
DOIs	https://doi.org/10.1016/j.epsl.2010.06.005
State	Published - Aug 2010
Externally published	Yes

Bibliographical note

Funding Information:
Research was supported by NSF ARC 0454906 . Postdoctoral funding for Newbrey was provided by the Royal Tyrrell Museum Cooperating Society and NSERC Discovery Grants A9180 (MVHW) and 327448 (AMM). Arctic fossils were collected in 1970s–2001 by M. Dawson, R. West, J.H. Hutchison, the late M. McKenna, and J.J.E, and are on loan to J.J.E. and M.G.N. from the Canadian Museum of Nature (K. Shepherd, M. Feuerstack) and the Nunavut Government (D. Stenton, J. Ross). Fig. 2 was created by Leigh Anne McConnaughey. The research benefited from discussions with M. Clementz, M. Dawson, G. Harrington, J. Basinger, P. Molnar, and the late M. McKenna. Comments from P. Delaney, D. Greenwood, and an anonymous reviewer greatly improved the manuscript. We dedicate the manuscript to the memory of Malcolm C. McKenna, renowned vertebrate paleontologist and a pioneer of Arctic paleontology.

Keywords

Coryphodon
Eocene Arctic paleoclimate
Fossil turtles
Oxygen isotopes
Seasonality

ASJC Scopus subject areas

Geochemistry and Petrology
Geophysics
Space and Planetary Science
Earth and Planetary Sciences (miscellaneous)

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10.1016/j.epsl.2010.06.005

Cite this

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title = "Seasonal variability in Arctic temperatures during early Eocene time",

abstract = "As a deep time analog for today's rapidly warming Arctic region, early Eocene (52-53. Ma) rock on Ellesmere Island in Canada's High Arctic (~79°N.) preserves evidence of lush swamp forests inhabited by turtles, alligators, primates, tapirs, and hippo-like Coryphodon. Although the rich flora and fauna of the early Eocene Arctic imply warmer, wetter conditions than at present, the quantification of Eocene Arctic climate has been more elusive. By analyzing oxygen isotope ratios of biogenic phosphate from mammal, fish, and turtle fossils from a single locality on central Ellesmere Island, we infer early Eocene Arctic temperatures, including mean annual temperature (MAT) of ~8 °C, mean annual range in temperature of ~16.5-19 °C, warm month mean temperature of 19-20 °C, and cold month mean temperature of 0-3.5 °C. Our seasonal range in temperature is similar to the range in estimated MAT obtained using different proxies. In particular, relatively high estimates of early Eocene Arctic MAT and SST by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in terrestrial soil bacteria and isoprenoid tetraether lipids in marine Crenarchaeota fall close to our warm month temperature, suggesting a bias towards summer values. From a paleontologic perspective, our temperature estimates verify that alligators and tortoises, by way of nearest living relative-based climatic inference, are viable paleoclimate proxies for mild, above-freezing year-round temperatures. Although for both of these reptilian groups, past temperature tolerances probably were greater than in living descendants.",

keywords = "Coryphodon, Eocene Arctic paleoclimate, Fossil turtles, Oxygen isotopes, Seasonality",

author = "Eberle, {Jaelyn J.} and Fricke, {Henry C.} and Humphrey, {John D.} and Logan Hackett and Newbrey, {Michael G.} and Hutchison, {J. Howard}",

note = "Funding Information: Research was supported by NSF ARC 0454906 . Postdoctoral funding for Newbrey was provided by the Royal Tyrrell Museum Cooperating Society and NSERC Discovery Grants A9180 (MVHW) and 327448 (AMM). Arctic fossils were collected in 1970s–2001 by M. Dawson, R. West, J.H. Hutchison, the late M. McKenna, and J.J.E, and are on loan to J.J.E. and M.G.N. from the Canadian Museum of Nature (K. Shepherd, M. Feuerstack) and the Nunavut Government (D. Stenton, J. Ross). Fig. 2 was created by Leigh Anne McConnaughey. The research benefited from discussions with M. Clementz, M. Dawson, G. Harrington, J. Basinger, P. Molnar, and the late M. McKenna. Comments from P. Delaney, D. Greenwood, and an anonymous reviewer greatly improved the manuscript. We dedicate the manuscript to the memory of Malcolm C. McKenna, renowned vertebrate paleontologist and a pioneer of Arctic paleontology. ",

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doi = "10.1016/j.epsl.2010.06.005",

language = "English",

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AU - Eberle, Jaelyn J.

AU - Fricke, Henry C.

AU - Humphrey, John D.

AU - Hackett, Logan

AU - Newbrey, Michael G.

AU - Hutchison, J. Howard

N1 - Funding Information: Research was supported by NSF ARC 0454906 . Postdoctoral funding for Newbrey was provided by the Royal Tyrrell Museum Cooperating Society and NSERC Discovery Grants A9180 (MVHW) and 327448 (AMM). Arctic fossils were collected in 1970s–2001 by M. Dawson, R. West, J.H. Hutchison, the late M. McKenna, and J.J.E, and are on loan to J.J.E. and M.G.N. from the Canadian Museum of Nature (K. Shepherd, M. Feuerstack) and the Nunavut Government (D. Stenton, J. Ross). Fig. 2 was created by Leigh Anne McConnaughey. The research benefited from discussions with M. Clementz, M. Dawson, G. Harrington, J. Basinger, P. Molnar, and the late M. McKenna. Comments from P. Delaney, D. Greenwood, and an anonymous reviewer greatly improved the manuscript. We dedicate the manuscript to the memory of Malcolm C. McKenna, renowned vertebrate paleontologist and a pioneer of Arctic paleontology.

PY - 2010/8

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N2 - As a deep time analog for today's rapidly warming Arctic region, early Eocene (52-53. Ma) rock on Ellesmere Island in Canada's High Arctic (~79°N.) preserves evidence of lush swamp forests inhabited by turtles, alligators, primates, tapirs, and hippo-like Coryphodon. Although the rich flora and fauna of the early Eocene Arctic imply warmer, wetter conditions than at present, the quantification of Eocene Arctic climate has been more elusive. By analyzing oxygen isotope ratios of biogenic phosphate from mammal, fish, and turtle fossils from a single locality on central Ellesmere Island, we infer early Eocene Arctic temperatures, including mean annual temperature (MAT) of ~8 °C, mean annual range in temperature of ~16.5-19 °C, warm month mean temperature of 19-20 °C, and cold month mean temperature of 0-3.5 °C. Our seasonal range in temperature is similar to the range in estimated MAT obtained using different proxies. In particular, relatively high estimates of early Eocene Arctic MAT and SST by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in terrestrial soil bacteria and isoprenoid tetraether lipids in marine Crenarchaeota fall close to our warm month temperature, suggesting a bias towards summer values. From a paleontologic perspective, our temperature estimates verify that alligators and tortoises, by way of nearest living relative-based climatic inference, are viable paleoclimate proxies for mild, above-freezing year-round temperatures. Although for both of these reptilian groups, past temperature tolerances probably were greater than in living descendants.

AB - As a deep time analog for today's rapidly warming Arctic region, early Eocene (52-53. Ma) rock on Ellesmere Island in Canada's High Arctic (~79°N.) preserves evidence of lush swamp forests inhabited by turtles, alligators, primates, tapirs, and hippo-like Coryphodon. Although the rich flora and fauna of the early Eocene Arctic imply warmer, wetter conditions than at present, the quantification of Eocene Arctic climate has been more elusive. By analyzing oxygen isotope ratios of biogenic phosphate from mammal, fish, and turtle fossils from a single locality on central Ellesmere Island, we infer early Eocene Arctic temperatures, including mean annual temperature (MAT) of ~8 °C, mean annual range in temperature of ~16.5-19 °C, warm month mean temperature of 19-20 °C, and cold month mean temperature of 0-3.5 °C. Our seasonal range in temperature is similar to the range in estimated MAT obtained using different proxies. In particular, relatively high estimates of early Eocene Arctic MAT and SST by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in terrestrial soil bacteria and isoprenoid tetraether lipids in marine Crenarchaeota fall close to our warm month temperature, suggesting a bias towards summer values. From a paleontologic perspective, our temperature estimates verify that alligators and tortoises, by way of nearest living relative-based climatic inference, are viable paleoclimate proxies for mild, above-freezing year-round temperatures. Although for both of these reptilian groups, past temperature tolerances probably were greater than in living descendants.

KW - Coryphodon

KW - Eocene Arctic paleoclimate

KW - Fossil turtles

KW - Oxygen isotopes

KW - Seasonality

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ER -

Seasonal variability in Arctic temperatures during early Eocene time

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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