Cenozoic megatooth sharks occupied extremely high trophic positions

Emma R Kast; Michael L Griffiths; Sora L Kim; Zixuan C Rao; Kenshu Shimada; Martin A Becker; Harry M Maisch; Robert A Eagle; Chelesia A Clarke; Allison N Neumann; Molly E Karnes; Tina Lüdecke; Jennifer N Leichliter; Alfredo Martínez-García; Alliya A Akhtar; Xingchen T Wang; Gerald H Haug; Daniel M Sigman

doi:10.1126/sciadv.abl6529

Cenozoic megatooth sharks occupied extremely high trophic positions

Sci Adv. 2022 Jun 24;8(25):eabl6529. doi: 10.1126/sciadv.abl6529. Epub 2022 Jun 22.

Authors

Emma R Kast^{1

2}, Michael L Griffiths³, Sora L Kim⁴, Zixuan C Rao¹, Kenshu Shimada^{5

6

7}, Martin A Becker³, Harry M Maisch⁸, Robert A Eagle⁹, Chelesia A Clarke³, Allison N Neumann³, Molly E Karnes⁴, Tina Lüdecke^{10

11}, Jennifer N Leichliter^{10

12}, Alfredo Martínez-García¹³, Alliya A Akhtar¹, Xingchen T Wang¹⁴, Gerald H Haug^{13

15}, Daniel M Sigman¹

Affiliations

¹ Department of Geosciences, Princeton University, Princeton, NJ 08544, USA.
² Department of Earth Sciences, University of Cambridge, Cambridge, CB23EQ, UK.
³ Department of Environmental Science, William Paterson University of New Jersey, Wayne, NJ 07470, USA.
⁴ Department of Life and Environmental Sciences, University of California Merced, Merced, CA 95343, USA.
⁵ Department of Environmental Science and Studies, DePaul University, Chicago, IL 60614, USA.
⁶ Department of Biological Sciences, DePaul University, Chicago, IL 60614, USA.
⁷ Sternberg Museum of Natural History, Fort Hays State University, Hays, KS 67601, USA.
⁸ Department of Marine and Earth Sciences, Florida Gulf Coast University, Fort Myers, FL 33965, USA.
⁹ Department of Atmospheric and Oceanic Sciences. Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA.
¹⁰ Emmy Noether Group for Hominin Meat Consumption, Max Planck Institute for Chemistry, 55128 Mainz, Germany.
¹¹ Senckenberg Biodiversity and Climate Research Centre, 60325 Frankfurt, Germany.
¹² Johannes Gutenberg University, Institute of Geosciences, 55128 Mainz, Germany.
¹³ Department of Climate Geochemistry, Max Planck Institute for Chemistry, 55128 Mainz, Germany.
¹⁴ Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA 02467, USA.
¹⁵ Department of Earth Sciences, ETH Zürich, CH-8092 Zürich, Switzerland.

Abstract

Trophic position is a fundamental characteristic of animals, yet it is unknown in many extinct species. In this study, we ground-truth the ¹⁵N/¹⁴N ratio of enameloid-bound organic matter (δ¹⁵N_EB) as a trophic level proxy by comparison to dentin collagen δ¹⁵N and apply this method to the fossil record to reconstruct the trophic level of the megatooth sharks (genus Otodus). These sharks evolved in the Cenozoic, culminating in Otodus megalodon, a shark with a maximum body size of more than 15 m, which went extinct 3.5 million years ago. Very high δ¹⁵N_EB values (22.9 ± 4.4‰) of O. megalodon from the Miocene and Pliocene show that it occupied a higher trophic level than is known for any marine species, extinct or extant. δ¹⁵N_EB also indicates a dietary shift in sharks of the megatooth lineage as they evolved toward the gigantic O. megalodon, with the highest trophic level apparently reached earlier than peak size.