Navigating the Drake Passage during the Eocene greenhouse to icehouse climate transition: a paleoecological and geochemical perspective based on sand tiger shark Striatolamia macrota teeth
- Autor(en)
- Sora L. Kim, Sarah S. Zeichner, Albert S. Colman, Howie D. Scher, Jürgen Kriwet
- Abstrakt
During the Eocene epoch, fundamental changes occurred in the Earth climate system that spurred the transition from greenhouse to icehouse conditions. Central to many explanations for this climate shift is the Southern Ocean—where tectonic configurations influenced oceanic gateways, ocean circulation reduced heat transport, and/or greenhouse gas declines prompted glaciation. Seymour Island is located off the Antarctic Peninsula and preserves a rich, diverse fossil assemblage in the Tertiary Eocene La Meseta (TELM) Formation (Fm). To date, there are few studies to explore the implications of this climate transition on high latitude, marine vertebrate taxa.
We combined paleontological and geochemical techniques to determine ecological changes and environmental conditions based on Striatolamia macrota, an ancient sandtiger shark that is the most dominant taxon throughout the La Meseta Fm. Body size, an important ecological trait that indicates energy balance and integrates physiological, environmental, and ontogenetic factors, was estimated based on anterior tooth crown height. We found no substantial shifts in body size distributions through TELMs 2-5 with mean ± 1s =19.6 ± 6.4 mm (n=450) and median = 18.0 mm, which corresponds to total body lengths (TL) ranging from 88 – 389 cm. Environmental conditions related to water temperature and ocean circulation were characterized based on oxygen and neodymium isotope composition, respectively. Further, oxygen isotope compositions from enameloid phosphate also indicate relatively stable water temperatures throughout this period with mean d18OPO4 value of 21.5 ± 1.6‰ (n=39) and translates to a mean temperature of 14.7 ± 3.7°C. This ecological and environmental stasis is especially intriguing given the eNd values (n=4), which vary approximately 1 eNd unit with an overall radiogenic trend. These preliminary eNd values are similar to previous results from deep ocean localities, but indicate an early Drake Passage opening with Pacific inputs as early as TELM 2. We hypothesize that S. macrota modified its migration behavior to preclude environmental changes related to the Drake Passage opening, which was likely a shallow continental shelf. Our results shed important light on paleoceanographic conditions and indicate paleoecological responses to climate change.- Organisation(en)
- Institut für Paläontologie
- Externe Organisation(en)
- University of California, Merced, California Institute of Technology (Caltech), Rice University, University of South Carolina, Columbia
- Anzahl der Seiten
- 1
- Publikationsdatum
- 12-2019
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105118 Paläontologie
- Sustainable Development Goals
- SDG 13 – Maßnahmen zum Klimaschutz
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/ffdda270-bad7-475b-832a-ea24fd6a004f