Knowra Oligocene Oligocene The Oligocene is the geological epoch from about 33.9 to 23 million years ago, between the Eocene and Miocene. It saw continued global cooling, Antarctic glaciation, and major changes in mammal communities.
Oligocene climate : The Oligocene climate was cooler and generally drier than that of the preceding Eocene, with a major Antarctic ice sheet. Cooling and Antarctic glaciation define the epoch’s largest environmental shift.
Geologic time scale : The chronological framework dividing Earth history into eons, eras, periods, epochs, and ages. It locates the Oligocene among Earth’s formally named intervals.
Grande Coupure : A major turnover in European mammal communities near the Eocene–Oligocene boundary, involving the arrival of Asian taxa. This sharp faunal change records how climate and migration transformed Oligocene Europe.
Cenozoic : The geological era spanning the past 66 million years, from the end of the Cretaceous to the present. The Oligocene forms part of the long-term environmental history of the Cenozoic.
Antarctic glaciation : The growth of large, persistent ice sheets on Antarctica, beginning around the Eocene–Oligocene transition. Antarctic ice growth drove a major fall in global sea level and temperatures.
Eocene : The geological epoch preceding the Oligocene, lasting from about 56 to 33.9 million years ago. Its warm climate contrasts with the cooling that began near the Oligocene boundary.
White River Formation : A sequence of Oligocene sedimentary rocks in the Great Plains of North America, rich in mammal fossils. Its fossils document the diverse mammals of Oligocene North America.
Mammal evolution : The evolutionary diversification and change of mammals through geological time. Oligocene cooling and habitat shifts influenced mammal distributions and forms.
Drake Passage : The ocean passage between the Antarctic Peninsula and South America, whose opening altered circulation around Antarctica. Its developing seaway helped establish circulation associated with Antarctic cooling.
Miocene : The geological epoch following the Oligocene, beginning about 23 million years ago. Its ecosystems and climate developed from conditions established during the Oligocene.
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