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The Oligocene (IPA: / ˈ ɒ l ɪ ɡ ə s iː n,-ɡ oʊ-/ OL-ə-gə-seen, -goh-) [4] is a geologic epoch of the Paleogene Period that extends from about 33.9 million to 23 million years before the present (33.9 ± 0.1 to 23.03 ± 0.05 Ma). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
The Oligocene is the third and youngest series/epoch of the Paleogene, and lasted from 33.9 Ma to 23.03 Ma. It is divided into two stages: the Rupelian 33.9 Ma to 27.82 Ma; and, Chattian 27.82 - 23.03 Ma. The GSSP for the base of the Oligocene is at Massignano, near Ancona, Italy.
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.
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.
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 ...
Map showing localities of Paraceratherium species during the early (yellow) and late (red) Oligocene, according to Deng and colleagues, 2021 Deng and colleagues speculated about the palaeobiogeography of Paraceratherium based on their phylogenetic analys in 2021.
The Eocene–Oligocene extinction event, also called the Eocene-Oligocene transition (EOT) or Grande Coupure (French for "great cut"), is the transition between the end of the Eocene and the beginning of the Oligocene, an extinction event and faunal turnover occurring between 33.9 and 33.4 million years ago. [1]
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]