DURHAM, N.C. – Sixty-three percent. That’s the proportion of mammal species that vanished from Africa and the Arabian Peninsula around 30 million years ago, after Earth’s climate shifted from swampy to icy. But we are only finding out about it now. Compiling decades of work, a new study published this week in the journal Communications Biology reports on a previously undocumented extinction event that followed the transition between the geological periods called the Eocene and Oligocene.