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Oligocene

Also known as Oligocene Series, Oligocene Epoch

The Oligocene is a geologic epoch of the Paleogene Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from Ancient Greek ὀλίγος (olígos), , and καινός (kainós), , and refers to the sparsity of extant forms of molluscs. The Olig

AI overview

The Oligocene is a geologic epoch that lasted from about 33.9 million to 23 million years ago and is part of the broader Paleogene Period. The epoch is named after the relatively small number of mollusk species from that time that still exist today, and scientists have identified the rock layers that mark this period, though the exact dates remain slightly uncertain.

AI-generated from the Wikipedia summary — may contain errors.

Key facts

Geologic timespan.name: Oligocene
Geologic timespan.color: Oligocene
Geologic timespan.time_start: 33.9
Geologic timespan.time_end: 23.04
Geologic timespan.image_map: Mollweide Paleographic Map of Earth, 30 Ma (Rupelian Age).png
Geologic timespan.caption_map: A map of Earth as it appeared 30 million years ago during the Oligocene Epoch, Rupelian Age
Geologic timespan.timeline: Paleogene
Geologic timespan.name_formality: Formal
Geologic timespan.name_accept_date: 1978
Geologic timespan.celestial_body: earth
Geologic timespan.usage: Global (ICS)
Geologic timespan.timescales_used: ICS Time Scale
Geologic timespan.chrono_unit: Epoch
Geologic timespan.strat_unit: Series
Geologic timespan.timespan_formality: Formal
Geologic timespan.lower_boundary_def: LAD of Planktonic Foraminifers Hantkenina and Cribrohantkenina
Geologic timespan.lower_gssp_location: Massignano quarry section, Massignano, Ancona, Italy
Geologic timespan.lower_gssp_accept_date: 1992

via Wikipedia infobox

Wikidata facts

Image: Indricotherium11.jpg

Show 4 more facts

start time: 33900000-0
Commons category: Oligocene
end time: 23030000-0
sRGB color hex triplet: FEC386

Sources (2)

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~27 min read

Article

23 sections

Contents

Boundaries and subdivisions
Tectonics and paleogeography
Climate
Eocene-Oligocene transition and Oi1 event
Middle Oligocene climate and the Oi2 event
Late Oligocene warming
Biosphere
Flora
Fauna
Oceans
Effects of oceanic gateways on circulation
Drake Passage
Opening of the Tasman Gateway
Tethys Seaway closing
Greenland–Iceland–Faroes
Ocean cooling
Deep water
Impact events
Supervolcanic explosions
See also
Notes
References
External links

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. Major changes during the Oligocene included a global expansion of grasslands, and a regression of tropical broad leaf forests to the equatorial belt.