extinction around 19 million years ago, which may have wiped out nearly 90 percent of the shark population at that time. This is particularly concerning as sharks have been resilient to large mass extinctions throughout their 420 million years of existence. The study, conducted by Elizabeth Sibert at Yale University and Leah Rubin at State University of New York College of Environmental Science and Forestry, found the first evidence of a mass extinction of "pelagic" sharks that reside in the open oceans.
The researchers isolated microfossils of shark scales, known as ichthyolith denticles, from mud samples taken from the sea floor in the North and South Pacific Ocean. These mud samples were collected from the upper 15 meters of the seafloor and were deposited over the past 40 million years. Sibert and Rubin analyzed a total of 1263 fossilized denticles and observed a sudden drop in the abundance and diversity of shark scales around 19 million years ago, during the Miocene epoch. This discovery sheds light on the vulnerability of pelagic sharks and highlights the threats they face from human activities such as overfishing, plastic pollution, and illegal shark finning.