This extinction occurred about 19 million years ago, and shark populations killed up to 90%, researchers say.
In a research paper published Thursday in Science at Yale University oceanographer and palaeontologist Elizabeth Seibert and Leah Rubin, then a student at the College of the Atlantic in Bar Harborand the Maine, that shark populations have not yet recovered from the sudden extinction.
Great white sharks thrive along the California coast
By studying the teeth of sharks and other microscopic marine fossils buried in deep-sea sediments in the Pacific Ocean, the man reportedly found them. The diversity of today’s sharks was just a “little remnant of a much larger group of forms” that was wiped out by the Miocene extinction.
Seibert told Fox News by email Saturday that she and Robin discovered the event “completely by chance.”
“I study the teeth of microfossil fish and shark scales – a particularly specialized group of microfossils in the very small field of microfossils – so not much is known about them,” she explained. “We decided to make a long list of abundances of fish and shark fossils, going back millions of years in the same place, just to see the natural contrast in the background. … What we found was that the ratio of fish teeth to shark skin scales (teeth) in the sediments was constant for more 40 million years ago (from about 60 million years ago to 19 million years ago), with one shark fossil for every 5 fish fossils.”
“But 19 million years ago that changed suddenly and dramatically, dropping to one shark fossil for every 100 or more fish teeth,” Seibert said. “Ninety million years ago, it wasn’t really known in geological history that it was a time of rapid environmental change – so we didn’t expect a change in the vertebrate community, let alone a mass extinction of sharks!”
However, the reason remains shrouded in mystery, the paper notes: “There is no known climate and/or ‘environmental driver’ for this extinction.”
The researchers noted that “modern sharks began to diversify within two million to five million years of extinction, but they represent only a small fraction of what sharks once were.”
The study also notes that the early Miocene was a period of “rapid and transformative change for open ocean ecosystems”.
“Like most research efforts, this first paper asks more questions than it can answer, and we plan to explore the breadth of data readouts through a variety of lenses from hydrodynamics to environment,” Rubin said in a Fox News quote.
The findings by Seibert and Rubin – now an incoming doctoral student at the State University of New York’s School of Environmental and Forest Sciences – reinforce the findings of a previous study using the same data collection.
In 2018, the journal published a separate group of scientists analyzing shark teeth from fossil deposits, Current Biology. The asteroid that wiped out the dinosaurs 66 million years ago also killed up to 34% of prehistoric shark species.
However, sharks have managed to survive for millions of years without major disturbances.
Although numbers of surface predators have declined in recent years, mainly due to: overfishing and other human pressures such as: climate change, recent reports from Pacific and Atlantic waters show that great white sharks are thriving.
Although “shark season” has just begun in 2021, more than 100 young white adults have already been marked. The coast of Northern California and a recent study Published in Biological Conservation It found that large numbers of whites in the Pacific rose significantly between 2011 and 2018.
The report’s authors also note that there has been a “similar regional increase in white shark populations in the United States.” Special Economic Zone From the Northwest Atlantic, citing: Research from 2014 what an optimistic view predicts the recovery of the Atlantic white shark.
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However, a January report in Nature found that the global abundance of oceanic sharks and rays has declined by 71% since 1970.
There are more than 500 species of sharks, according to the Smithsonian Institution’s Ocean Portal, and an estimated 100 million people die each year from fishing.
