This epoch is part of theTertiary period and the
The Oligocene Epoch is a period of time that extends from about 33.7 million to 23.8 million years before the present. As with other older geologic periods, the rock beds that define the start and end are well identified, but the exact dates of the start and end of the period are slightly uncertain. The name Oligocene refers to the sparsity of additional modern mammalian faunas after a burst of evolution during the Eocene. The Oligocene follows the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third epoch of the Tertiary Era.
The start of the Oligocene is marked by a major extinction event that may be related to the impact of large extraterrestrial object in Siberia and/or near Chesapeake Bay. The Oligocene-Miocene boundary is not set at an easily identified worldwide event but rather at regional boundaries between the warmer Oligocene and the relatively cooler Miocene.
Oligocene faunal stages from youngest to oldest are: