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An early Miocene extinction in pelagic sharks
Elizabeth C Sibert1,2,3, Leah D Rubin4
1Harvard Society of Fellows, Harvard University, Cambridge, MA 02138, USA. elizabeth.sibert@yale.edu.
Science (New York, N.Y.)
|June 4, 2021
Summary
A major shark extinction event occurred ~19 million years ago, causing a >90% decline in abundance and >70% loss in diversity. This ancient marine predator crisis reshaped open-ocean ecosystems.
Area of Science:
- Paleontology
- Marine Biology
- Oceanography
Background:
- Shark populations face modern threats from overfishing and anthropogenic stressors.
- Long-term impacts of marine predator changes are not well understood.
- Previous research has not identified major ancient shark extinction events.
Purpose of the Study:
- To identify and characterize a previously unknown major extinction event in sharks.
- To determine the timing and scale of this ancient shark population decline.
- To understand the implications for early Miocene open-ocean ecosystems.
Main Methods:
- Analysis of shark abundance and morphological diversity in early Miocene open-ocean sediments.
- Correlation of extinction event with known global climate events.
- Comparison of extinction timing with subsequent predator diversifications.
Main Results:
- Evidence for a major shark extinction event around 19 million years ago (early Miocene).
- Shark abundance declined by over 90%, and morphological diversity by over 70%.
- This extinction was independent of known global climate events and preceded major predator diversifications.
Conclusions:
- The early Miocene experienced a significant, transformative event for open-ocean ecosystems, marked by a drastic reduction in shark populations.
- This ancient extinction event fundamentally altered marine predator dynamics.
- Sharks have not recovered to their pre-extinction abundance or diversity levels in open-ocean environments.
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