Sunday, October 26, 2014

Earth's largest shark disappeared 2.6 million years ago

An ancient shark, the largest to ever live, likely went extinct about 2.6 million years ago, scientists have found. 

While researchers do not know why giant, 60-foot-long Megalodon sharks went extinct, scientists now have a better estimate for when it happened. 

Most Megalodon fossils date back to the middle Miocene Epoch (15.9 million to 11.6 million years ago) and the Pliocene Epoch (5.3 million to 2.6 million years ago). 

The researchers in the new study identified 42 of the most recent fossils after sorting through the Paleobiology Database - a large online compilation of fossil data. 

The team used the Optimal Linear Estimation (OLE) technique to estimate when the Megalodon died out, 'Live Science' reported. 

Each of the 42 fossils was entered into the database with an upper and lower date estimate for when it appeared. The researchers ran 10,000 simulations, and each simulation selected a date for each fossil somewhere between the upper and lower boundary. 

The technique doesn't pinpoint the exact date when a species went extinct, but instead gives the date by which, statistically, it can be assumed that a species has gone extinct, said Chris Clements, a research assistant at the University of Zurich, who worked on the study. 

"We get 10,000 estimates for the time the species has gone extinct by, and then we look at the distribution of those estimates through time," Clements said. 

The idea is to identify the point where most of the estimates cluster. The results for the Megalodon fossils placed that point for this species at 2.6 million years ago. 

The findings are published in the journal PLOS ONE.

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