Mass Extinction Event Revealed by Ancient Rocks from the Great Karoo

Ancient rocks from the Great Karoo shed some light on a mass extinction event that occurred around 260 million years ago. Researchers have obtained the age of the rocks and have found out a bit more about what occurred at the time.

The Karoo is rich in fossils of terrestrial animals from the Permian and Triassic periods. This makes it one of the few places to study extinction events on land during this time. As a result, South Africa's Karoo region provides not only a historical record of biological change over a period of Earth's history, but also a means to test theories of evolutionary processes.

In this case, the researchers examined fossils in the region. This revealed that 74 to 80 percent of species became extinct along with dinocephalians in a geologically short period of time.

"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 Michael Day, one of the researchers, in a news release. "The new date 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."

The mid-Permian extinction occurred at the end of the Guadalupian epoch. It pre-dated the more famous end-Permian mass extinction event by 8 million years.

"The South African Karoo rocks host the richest record of middle Permian land-living vertebrate animals," said Day. "This dataset, the culmination of 30 years of fossil collecting and diligent stratigraphic recording of the information, for the first time provides robust fossils and radioisotopic data to support the occurrence of this extinction event on land."

The findings are published in the journal Proceedings of the Royal Society B.

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