A new study found that a mysterious event nearly 19 million years ago wiped out the entire shark population. Scientists supporting the new study said that studies of shark teeth buried in deep-sea sediments show that the current diversity among sharks is only a small part of the larger species that existed at the time. They say that this unidentified ocean extinction has reduced the diversity of sharks by more than 70% and almost completely lost the total population. Scientists say that the cause of this incident is still a mystery.
The researchers said that this single event caused the sharks to almost disappear from the high seas sediments, reducing the number by nearly 90%. They added that the sudden extinction has nothing to do with any known global climate events.
According to a research report published in the journal Science, modern shark morphology began to diversify within 2 to 5 million years after being on the brink of extinction, but they only represent a small part of the sharks of the past.
A report in Life Sciences quoted Elizabeth Siebert, a postdoctoral fellow at Yale University’s Biosphere Institute and co-author of the study, as saying: “Sharks have existed for 400 million years; they have withstood many mass extinctions.”
Sibert told Live Science that the study of microscopic fossils of ichthyrites and shark scales was found in most types of sediments, but they were small and relatively rare compared with other microfossils, which led to this discovery.
Although scientists in the 1970s and 1980s studied ichthyrite, only a few researchers studied it before Sibert, who completed her PhD study in 2016. Figure out how to deal with these fossils and what kind of questions we can ask,” Sibert said.
In their new research, Sibert and Leah Rubin, undergraduates at Atlantic College in Bar Harbor, Maine, studied sedimentary cores extracted from deep-sea drilling projects many years ago. From two different locations: one in the middle of the North Pacific and the other in the middle of the South Pacific.
“We chose these locations mainly because they are far away from land and away from any effects of ocean circulation or changes in ocean currents,” Sibert said.
Rubin, who will now be a doctoral student in the School of Environmental Science and Forestry at the State University of New York, said that the extreme nature of shark diversity is also the most surprising aspect of the study. Rubin said, what caused this multi-million dollar problem?
Sibert said that this paper is just the beginning, and hopes that in the next ten years, we can learn more about the reasons that led to the extinction of sharks. This will be a very interesting process.