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When did Antarctica begin developing continental-scale ice sheets?
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Cenozoic Era
Principal Cenozoic faunal migration routes and barriers.
During the Cenozoic Era, a continental ice sheet first developed in Antarctica during the Oligocene Epoch. This ice sheet persisted until a rapid warming event occurred 27 million years ago. Following a relatively warm period during the late Oligocene and early to mid-Miocene epochs, cooling resumed 15 million years ago, leading the Antarctic Ice Sheet to expand once again to cover much of the continent.1