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Scientists have discovered a previously unknown shark mass extinction event that wiped out the global population of these marine predators about 19 million years ago. It is currently a mystery what happened to the shark population, but the authors of the study say that as a result of this event, sharks almost completely disappeared from the world's oceans.

Sharks and their ancestors have been swimming in the Earth's oceans for the past 450 million years. They are an unusually resilient life form that has survived many extinction events and is now among the top predators in Earth's modern oceanic world.

The results of a recently published study have opened a new chapter in the history of these ancient predators, during which their populations were devastated on a global scale.

The discovery was made by researchers from Yale University and Atlantic College in Bar Harbor, who compiled an 85-million-year fossil record of shark abundance to better understand how their populations varied over vast areas and over time.

The record showed a 40-million-year period of relative stability, during which the ratio of sharks to fish in the fossil record fluctuated at 1: 5.

However, around 19 million years ago, this ratio changed dramatically by one shark fossil to 100. This discovery points to a period of sudden widespread changes in the ancient ecosystem of the world's oceans.

According to the authors of the study, the mysterious event led to the disappearance of about 70 percent of all sharks – about twice as many as after the collision with the asteroid Chicxulub about 66 million years ago, which led to the death of the dinosaurs.

In addition, the mortality rate among sharks living in the open ocean was significantly higher compared to populations living in coastal regions.

The reason for the extinction of sharks currently remains a mystery. This happened at a time that is considered relatively stable in the history of our planet, when the Earth's ecosystems were undergoing relatively small transformations and no disasters such as asteroid impacts were recorded.

"The current state of decline in shark populations is certainly worrisome, and this paper helps put this decline in the context of shark populations over the past 40 million years," explained study co – author Leah Rubin.

"This context is an important first step in understanding what the consequences may be due to the dramatic decline in the numbers of these higher marine predators in our time."

A scientific article about the study was published in the journal Science.

ab-news.ru