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The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period. The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. [9]
The end of the Eocene and beginning of the Oligocene is marked with the massive expansion of area of the Antarctic ice sheet that was a major step into the icehouse climate. [106] Multiple proxies, such as oxygen isotopes and alkenones , indicate that at the Eocene–Oligocene transition, the atmospheric carbon dioxide concentration had ...
A brief marine incursion marks the early Oligocene in Europe. There appears to have been a land bridge in the early Oligocene between North America and Europe since the faunas of the two regions are very similar. During the Oligocene, South America was finally detached from Antarctica and drifted north toward North America.
A map of Earth as it appeared 45 ... The Oligocene is the third and youngest series/epoch of the Paleogene, and lasted from 33.9 Ma to 23.03 Ma. ... The locations of ...
The epoch is bracketed by two major events in Earth's history. The K–Pg extinction event, brought on by an asteroid impact (Chicxulub impact) and possibly volcanism (Deccan Traps), marked the beginning of the Paleocene and killed off 75% of species, most famously the non-avian dinosaurs.
The Eocene-Oligocene Boundary 33.9 million years ago was the transition from the last greenhouse period to the present icehouse climate. [ 17 ] [ 18 ] [ 10 ] At this point, when ~25% more of Antarctica's surface was above sea level and able to support land-based ice sheets relative to today, [ 19 ] CO 2 levels had dropped to 750 ppm. [ 20 ]
The Western North American floras of the Eocene were divided into four floral "stages" by Jack Wolfe based on work with the Puget Group plant fossils.The four stages, Franklinian, Fultonian, Ravenian, and Kummerian covered the Early Eocene through early Oligocene, and three of the four were given informal early/late substages.
Map of "Europe" in the early Oligocene, some 30 million years ago. The formation of Europe as a coherent landmass dates to after the breakup of Pangaea, taking place during the Oligocene and completed by the early Neogene period, some 20 million years ago.