Definition of Oligocene in US English:



  • 1Relating to or denoting the third epoch of the Tertiary period, between the Eocene and Miocene epochs.

    The Oligocene epoch lasted from 35.4 million to 23.3 million years ago. It was a time of falling temperatures, with evidence of the first primates

    • ‘The Miocene saw the continuation of bioregional provinces in some instances, and great mammal migrations in other cases, as animals that had evolved on different continents during the Eocene and Oligocene spread via land-bridges.’
    • ‘Most perissodactyl lineages went extinct in the late Eocene or Oligocene.’
    • ‘The diversity seen during the late Oligocene and early Miocene drops, and dugongs are apparently not well represented after the middle Miocene.’
    • ‘Comparable deformation in the Canadian Arctic began in the Late Cretaceous and continued into Oligocene time.’
    • ‘Profiles through the summit of a small nearly axisymmetric extrusion of Oligocene and Miocene salt, and simple analogue models of it, simulate the profiles of piles of ductile nappes extruded from convergent orogens.’
    • ‘The oldest fossilized vertebrate burrows discovered are known from deposits in Wyoming and Nebraska associated with the Oligocene epoch, the period between 33.7 million and 23.8 million years ago.’
    • ‘Leakoff tests had been carried out in each of the four wells within either the Lower Miocene or the Oligocene interval.’
    • ‘The paucity of Oligocene and Miocene records is probably due to collecting bias and limited area of outcrop.’
    • ‘In the North Pacific, most invaders during the late Eocene to early Oligocene spread from west to east, from East Asia to the west coast of North America.’
    • ‘In profiles though the summit, Qum Kuh can be considered as a pile of recumbent fold nappes of gneissose and mylonitic Oligocene and Miocene salts that have extruded from depth and gravity spread over recent gravels.’
    • ‘The global cooling trend that began in the Oligocene epoch and accelerated in the Miocene and Pliocene was catastrophic for the crocodiles.’
    • ‘In the Sahara, aridity was initially established in the late Cretaceous in the northwestern Sahara and in the main Sahara during the Oligocene, as revealed by the presence of aeolian sand in Oligocene ocean cores off NW Africa.’
    • ‘The test reported here uses well data to find this effective stress ratio in four North Sea wells penetrating Oligocene and Miocene sequences that contain polygonal fault networks.’
    • ‘The oreodonts, sheep-like artiodactyls from the Eocene and Oligocene, were among these early artiodactyls.’
    • ‘This observation suggests that this relief was initiated before the Paleocene to Oligocene Pyrenean compression, certainly during the early spreading phase.’
    • ‘Frost and coworkers mapped late Oligocene and early Miocene reef deposits from fringing/barrier reef complexes in Chiapas and Puerto Rico and tracts of small patch reefs on carbonate platforms in Antigua and Texas.’
    • ‘The bulk of the sediments on the outer margin are of Eocene to Oligocene age with thin units of younger sediments on top.’
    • ‘The fossil record of this family extends to the late Eocene or early Oligocene.’
    • ‘It includes the Palaeocene, Eocene, and Oligocene epochs, spanning the time from the end of the Mesozoic to the beginning of the Neogene, i.e. from 65 Ma to 23 Ma.’
    • ‘The Maghrebian belt, forming the main part of Sicily, consists of Permian to Oligocene shelf and basinal carbonate successions, followed by younger terrigenous deposits.’
    1. 1.1as noun the Oligocene The Oligocene epoch or the system of rocks deposited during it.


Mid 19th century: from oligo- ‘few’ + Greek kainos ‘new’.