Mass extinction 260m years ago, according to Karoo discovery

8 Jul 2015

Two separate extinctions — one on land and one under the sea — have now been linked together as one mass event following years of research in the Great Karoo in South Africa.

The discovery shows that almost all of the Earth’s species – including Dinocephalians, the largest land-living animals at the time – died out 260 million years ago.

Wits University researchers led an international team in obtaining an age from the rocks of the Great Karoo that now links South Africa’s fossil record with the fossil record of global equivalents.

Indeed, the Karoo has an abundance of fossils from the Permian and Triassic periods, making it one of the rare places on Earth to look into animal extinctions during this time.

The researchers, led by Dr Michael Day, a postdoctoral fellow at Wits University, now reckon up to 80pc of the planet’s species died off in a “short period of time”.

Guadalupian extinction

An illustration of the Guadalupian extinction, via Wits University

“A mid-Permian extinction event on land has been known for some time but was suspected to have occurred earlier than those in the marine realm,” said Day.

“The new data suggests that one event may have affected marine and terrestrial environments at the same time, which could mean its impact was greater than we thought.

“This dataset, the culmination of 30 years of fossil collecting and diligent stratigraphic recording of the information, for the first time provides robust fossil and radioisotopic data to support the occurrence of this extinction event on land,” added Day.

Prof Bruce Rubidge standing on an ash horizon near Beaufort West, which was dated at around 260 million years old. Credit_Wits University

Prof Bruce Rubidge standing on an ash horizon, dated as 260m years old, via Wits University

The mid-Permian extinction occurred near the end of what geologists call the Guadalupian epoch that extended from 272.3 to around 259.1 million years ago.

It pre-dated the massive and much more famous end-Permian mass extinction event by eight million years.

“The exact age of the marine extinctions remains uncertain,” said Jahandar Ramezani of Massachusetts Institute of Technology, who was responsible for dating the rocks.

“But this new data from terrestrial deposits of the Karoo, supported by palaeontological evidence, represents an important step towards a better understanding of the mid-Permian extinction and its effect on terrestrial faunas.”

Paleontologist Dr Michael Day, Wits University, via Brett Eloff.

Paleontologist Dr Michael Day, Wits University, via Brett Eloff.

The study has been published in Royal Society Publishing.

Main image of Great Karoo, via Shutterstock

Gordon Hunt was a journalist with Silicon Republic