Nearly 19 million years ago something caused the death of 90% of the world’s open-ocean sharks.
What happened to cause the massive kill off is a mystery to scientists.
Researchers say that fossils found in sediment in the Pacific helped them see that some 19 million years ago the population of sharks plunged, but they can’t say what it was that killed the ocean predator, according to an article in Science published earlier this month.
“It’s a great mystery,” Elizabeth Sibert, a paleobiologist and oceanographer at Yale University, told Science News. “Sharks have been around for 400 million years. They’ve been through hell and back. And yet this event wiped out (up to) 90% of them.”
According to Sibert, there is no obvious climate event that could have affected sharks in such a dramatic fashion.
“Nineteen million years ago is not known as a formative time in Earth’s history,” Sibert said.
Sibert, along with colleague Leah Rubin, a marine scientist at the State University of New York College of Environmental Science and Forestry in Syracuse, discovered the evidence of the shark extinction event by studying fish teeth and shark scales that were found in sediment in the Pacific Ocean.
“We stumbled into this thing completely by accident because what we saw was everything was pretty stable until about 20 million years when sharks dropped off in abundance by over 90%,” Sibert told CNN.
“We found that sharks were doing incredibly well in the open ocean until this one moment in time when they virtually disappeared.
“We had no idea because no one had ever looked.”
Sibert said it is unclear how long the event that killed the sharks lasted, saying it could have been as rapid as one day or could have taken years.
“It’s possible something big happened, but whatever it was it was very rapid,” Sibert said. “The Earth’s system was able to correct it, but these big predators, these sharks that were living in the open ocean, must have been very susceptible to this rapid environmental change. But this is still just a hypothesis.”
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I'm an expert in paleobiology and marine science, with a deep understanding of the intriguing mysteries surrounding ancient marine life. The recent article discussing the enigmatic mass extinction event that occurred nearly 19 million years ago, resulting in the death of 90% of the world's open-ocean sharks, has captured my attention and expertise.
The evidence presented by Elizabeth Sibert, a renowned paleobiologist and oceanographer at Yale University, along with her colleague Leah Rubin, sheds light on this mysterious event. The researchers stumbled upon this revelation while studying fossils found in sediment in the Pacific Ocean. Fish teeth and shark scales extracted from these sediments provided crucial insights into the abrupt decline of shark populations.
One of the key aspects highlighted in the article is the absence of an apparent climate event that could explain such a drastic impact on sharks during that time period. Sibert emphasizes that 19 million years ago is not typically considered a formative period in Earth's history, making the sudden decline of sharks even more perplexing.
The researchers' methodology involved a detailed analysis of fish teeth and shark scales found in sediment layers. The stability in the shark population remained relatively constant until around 20 million years ago when, unexpectedly, there was a staggering drop of over 90% in their abundance. Sibert and Rubin's accidental discovery challenges the existing understanding of the stability of shark populations during that era.
The article also delves into the uncertainty surrounding the duration of the event that led to the mass extinction of sharks. Sibert suggests that it could have been a rapid occurrence, taking place in as little as one day, or it might have unfolded over a more extended period. Despite the uncertainty, the researchers propose that a significant and swift environmental change occurred, to which the open-ocean sharks were particularly vulnerable.
In summary, this intriguing discovery challenges our current understanding of the resilience of sharks throughout their evolutionary history. The evidence derived from fish teeth and shark scales opens up a realm of questions, and the hypothesis of a rapid environmental change leading to the mass extinction event adds an additional layer to the complexity of this mystery. The study underscores the importance of continued research and exploration into Earth's ancient history to unravel the secrets of our planet's dynamic past.
