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Probing the Ecology and Climate of the Eocene Southern Ocean With Sand Tiger Sharks Striatolamia macrota

Kim, Sora L. and Zeichner, Sarah S. and Colman, Albert S. and Scher, Howie D. and Kriwet, Jürgen and Mörs, Thomas and Huber, Matthew (2020) Probing the Ecology and Climate of the Eocene Southern Ocean With Sand Tiger Sharks Striatolamia macrota. Paleoceanography and Paleoclimatology, 35 (12). Art. No. e2020PA003997. ISSN 2572-4517. https://resolver.caltech.edu/CaltechAUTHORS:20201106-125108320

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Abstract

Many explanations for Eocene climate change focus on the Southern Ocean—where tectonics influenced oceanic gateways, ocean circulation reduced heat transport, and greenhouse gas declines prompted glaciation. To date, few studies focus on marine vertebrates at high latitudes to discern paleoecological and paleoenvironmental impacts of this climate transition. The Tertiary Eocene La Meseta (TELM) Formation has a rich fossil assemblage to characterize these impacts; Striatolamia macrota, an extinct (†) sand tiger shark, is abundant throughout the La Meseta Formation. Body size is often tracked to characterize and integrate across multiple ecological dimensions. †S. macrota body size distributions indicate limited changes during TELMs 2–5 based on anterior tooth crown height (n = 450, mean = 19.6 ± 6.4 mm). Similarly, environmental conditions remained stable through this period based on δ¹⁸O_(PO4) values from tooth enameloid (n = 42; 21.5 ± 1.6‰), which corresponds to a mean temperature of 22.0 ± 4.0°C. Our preliminary ε_(Nd) (n = 4) results indicate an early Drake Passage opening with Pacific inputs during TELM 2–3 (45–43 Ma) based on single unit variation with an overall radiogenic trend. Two possible hypotheses to explain these observations are (1) †S. macrota modified its migration behavior to ameliorate environmental changes related to the Drake Passage opening, or (2) the local climate change was small and gateway opening had little impact. While we cannot rule out an ecological explanation, a comparison with climate model results suggests that increased CO₂ produces warm conditions that also parsimoniously explain the observations.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2020pa003997DOIArticle
https://doi.org/10.6071/M34T1ZDOIData
ORCID:
AuthorORCID
Kim, Sora L.0000-0002-4900-3101
Zeichner, Sarah S.0000-0001-8897-7657
Colman, Albert S.0000-0002-8220-8280
Scher, Howie D.0000-0002-7778-6772
Kriwet, Jürgen0000-0002-6439-8455
Mörs, Thomas0000-0003-2268-5824
Huber, Matthew0000-0002-2771-9977
Additional Information:© 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Issue Online: 08 December 2020; Version of Record online: 08 December 2020; Accepted manuscript online: 06 November 2020; Manuscript accepted: 01 November 2020; Manuscript revised: 20 October 2020; Manuscript received: 02 June 2020. We thank Dr. Patricia Holroyd at the University of California Museum of Paleontology for her introduction to the sand tiger sharks of Seymour Island and especially her encouragement and support of SLK. In addition, we thank Leslie Skibinski and Dr. Greg Dietl at the Paleontological Research Institution for access to the Zinsmeister Antarctica Collection as well as Leslie Skibinski and Dr. Jeffrey Stilwell for associated locality information. For teeth collected in recent expeditions, we thank the Argentine Antarctic Institute (IAA‐DNA), especially Dr. Marcelo Reguero and the Argentine Air Force for logistical fieldwork support and the great hospitality at the Marambio Base; the Swedish Polar Research Secretariat (SPFS) for logistical support; and Dr. Federico Degrange, Jonas Hagström, Juan‐José Moly, Dr. José O'Gorman, and Dr. Claudia Tambussi for assistance in the field. Financial support to TM for field work from the Swedish Research Council (VR Grant 2009‐4447) is gratefully acknowledged. Financial support was provided by the Austrian Science Fund (FWF, grant P26465‐B25) to JK; National Science Foundation to SLK (NSF OPP 1842049), ACS (NSF MRI 0923831), HDS (NSF OPP 1842176), and MH (NSF OPP 1842059). We also thank Dr. Linda Ivany for her ongoing conversations and feedback that shaped many dimensions of this project as well as Dr. Peter Bijl and Dr. Alex Farnsworth for their thoughtful and constructive reviews. Data Availability Statement. All data and model results can be found online (https://doi.org/10.6071/M34T1Z).
Funders:
Funding AgencyGrant Number
Swedish Research Council2009-4447
FWF Der WissenschaftsfondsP26465-B25
NSFOPP-1842049
NSFMRI-0923831
NSFOPP-1842176
NSFOPP-1842059
Subject Keywords:paleoclimate; oxygen isotope analysis; Seymour Island; paleobiology; temperature; neodymium isotope analysis
Issue or Number:12
Record Number:CaltechAUTHORS:20201106-125108320
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20201106-125108320
Official Citation:Kim, S. L., Zeichner, S. S., Colman, A. S., Scher, H. D., Kriwet, J., Mörs, T., & Huber, M. (2020). Probing the ecology and climate of the Eocene Southern Ocean with sand tiger sharks Striatolamia macrota. Paleoceanography and Paleoclimatology, 35, e2020PA003997. https://doi.org/10.1029/2020PA003997
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106495
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:06 Nov 2020 21:28
Last Modified:09 Dec 2020 22:47

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