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The Paleogene Period (IPA: / ˈ p eɪ l i. ə dʒ iː n,-l i. oʊ-, ˈ p æ l i-/ PAY-lee-ə-jeen, -lee-oh-, PAL-ee-; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period 66 Ma (million years ago) to the beginning of the Neogene Period 23.03 Ma.
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 ...
It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek παλαιός palaiós meaning "old" and the Eocene Epoch (which succeeds the Paleocene), translating to "the old part of the Eocene". The epoch is bracketed by two major events in Earth's history.
The Cretaceous–Paleogene (K–Pg) extinction event, [a] also known as the K–T extinction, [b] was the mass extinction of three-quarters of the plant and animal species on Earth [2] [3] approximately 66 million years ago. The event caused the extinction of all non-avian dinosaurs.
c. 66.038 ± 0.011 Ma – Cretaceous-Paleogene extinction event at the end of the Cretaceous Period marks the end of the Mesozoic era and the age of the dinosaurs; start of the Paleogene Period and the current Cenozoic era.
The K–Pg boundary marks the end of the Cretaceous Period, the last period of the Mesozoic Era, and marks the beginning of the Paleogene Period, the first period of the Cenozoic Era. Its age is usually estimated at 66 million years, [2] with radiometric dating yielding a more precise age of 66.043 ± 0.043 Ma. [3]
The Danian is the oldest age or lowest stage of the Paleocene Epoch or Series, of the Paleogene Period or System, and of the Cenozoic Era or Erathem. The beginning of the Danian (and the end of the preceding Maastrichtian) is at the Cretaceous–Paleogene extinction event. The age ended , being followed by the Selandian. [5]
Nevertheless, much of the research occurring during this period lacked rigor, evidential support or depended on tenuous assumptions. [8] Michael J. Benton called the years between 1920 and 1970 the "Dilettante Phase" of Cretaceous–Paleogene extinction research. [4]