Home / Science / An unknown mass extinction of sharks 19 million years ago was discovered by accident by researchers.

An unknown mass extinction of sharks 19 million years ago was discovered by accident by researchers.



Sharks have been around for half a billion years. They were close before the tree existed. They survived a series of mass extinction events that wiped out almost all other creatures from Earth. By any measure, they are one of the most successful breeds in the world.

And a surprising new discovery has revealed that they are on the brink of a perilous disappearance. And they still haven’t recovered from the effects.

“We stumbled upon this by accident!” Head of Education Elizabeth Sibert told IFLS via email.[W]I didn’t expect to see any changes in the shark community, less is mass extinction!”

Sibert, together with study co-author Leah Rubin, made the discovery while studying microfossil teeth and shark scales, Sibert explains. Little is known about this relatively specific area of ​​paleontology. And the primary aim of the project is to better understand the biodiversity of the natural oceans.

“We decided to create a long-standing record of the fossil abundance of fish and sharks. by going back millions of years in the same place to see what the normal background looks like,”

; Sibert said.[I]It’s important to get an idea of ​​the ‘basics’ before dealing with the potential impact of global change events.”

The study found that For tens of millions of years, the shark’s fish-fossil ratio has remained constant. Basically about one shark fossil for every five fish fossils, but then 19 million years ago disaster struck. The ratio was reduced to less than one shark fossil for every hundred fish, reflecting a decline of more than 90 percent in the number of sharks.

Almost everything about this discovery was surprising. the moment that happened “Previously unusual,” commented on Science, palaeontologists Catalina Pimiento and Nicholas D. Pyenson, who were not involved in the original study. They noted the cause of this “extinction of the wholesale shark pedigree in … the largest ecosystems in the world” is something that researchers have yet to reveal.

Sibert and Rubin’s report, published last week in Science, said: “There are no known climate and/or environmental drivers. And the cause of its extinction remains a mystery.” “Modern shark patterns … are just a tiny fraction. of what the shark used to be.”

In fact, Sibert explains, we have no clear idea of ​​the extent of the disaster. The results showed that sharks were greatly affected by the incident. but will affect other parts of the ocean ecosystem? and if so How not to know

and the fact that the number and diversity of shark populations have not recovered from that event. It’s another mystery that scientists have to face.

“We’re not sure why shark populations and diversity didn’t recover after the event,” Sibert told IFLS. Sharks have adapted to new environments or environments. less than other large aquatic animals such as whales, so in the new other living things can spread more quickly and Evolve and defeat the surviving sharks effectively.”

“Like most research This first document has more questions than can be answered,” Rubin added.

But unexpected discoveries are not only important to our understanding of the past. but also a clear message for the future. Marine predators such as sharks and whales are dying at an alarming rate. And the findings may provide insights into the impact it will have on other ocean life.

“The current state of the declining shark population is certainly cause for concern,” Rubin said. [paper] It is an important first step in understanding the potential consequences of the dramatic decline of these top marine predators in modern times.”

The consequences are something we may soon discover for ourselves – but these new findings may shed light on what to expect. the author explains

“[S]Hark … plays a very important role in marine ecosystems. and when its number decreases It can turn the ecosystem into a completely new condition. even though it has been stable for tens of millions of years,” cautions Sibert. “Humans are rapidly reducing the population of most large vertebrate predators in today’s oceans. I’m afraid we’re running towards a turning point. Perhaps the same as what we observed 19 million years ago.”

But for Sibert and Rubin The future is exciting

“…[T]There is so much more to learn about the world,” Sibert said. “Sharks have been around for more than 400 million years, yet unprecedented events nearly wiped them out of the oceans only 19 million years ago. We don’t know because we haven’t seen it.”

“There is always more to find out,” she added. “What next?”


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