Friday 31 October, 2014

Specific time and rate of Earth’s most extreme extinction revealed

Published On: Fri, Nov 18th, 2011 | Geology | By BioNews

A team of researchers from North America and China has for the first time identified the exact date and rate of Earth’s most severe mass extinction.

About 95 percent of marine life and 70 percent of terrestrial life became extinct during what is known as the end-Permian, a time when continents were all one land mass called Pangea.

It’s well understood that this mass extinction occurred about 250 million years ago, but the specific time when the extinctions occurred has remained known.

“This is the first paper to provide rates of such massive extinction,” said Dr. Charles Henderson, professor in the Department of Geoscience at the University of Calgary and co-author of the study.

“Our information narrows down the possibilities of what triggered the massive extinction and any potential kill mechanism must coincide with this time,” he noted.

Through the analysis of various types of dating techniques on well-preserved sedimentary sections from South China to Tibet, researchers determined that the mass extinction peaked about 252.28 million years ago and lasted less than 200,000 years, with most of the extinction lasting about 20,000 years.

“These dates are important as it will allow us to understand the physical and biological changes that took place,” said Henderson.

“We do not discuss modern climate change, but obviously global warming is a biodiversity concern today. The geologic record tells us that ‘change’ happens all the time, and from this great extinction life did recover,” he noted.

The study concluded that extinctions of most marine and terrestrial life took place at the same time. And the trigger, as suggested by these researchers and others, was the massive release of CO2 from volcanic flows known as the Siberian traps, now found in northern Russia.

The findings have been published in Science this week.

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