Up to 63% of African and Arabian mammal species may have vanished in a previously undetected die-off.
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Nearly two-thirds of the mammal species known in Europe and Asia at that time went extinct. Still, scientists previously thought African and Arabian mammals may have escaped this fate -- the area's mild climate and proximity to the equator could have served as a buffer from the worst of the cooling trend.
"I was really surprised to find that the same pattern of extinction emerged in each of the five different groups we had trees for, each of which had independent origins in Africa," said study senior author Erik Seiffert, an evolutionary biologist at the University of Southern California. Previous research might have missed this mass extinction by focusing on sudden die-offs that could be tied directly to a major climate shift right at the Eocene-Oligocene boundary, Seiffert said. In contrast, this gradual mass extinction may have been due to environmental degradation and habitat loss over the course of 4 million years due to climate and other shifts, "so we needed to really zoom out and take a broader view to appreciate the pattern," he noted.