Smithsonian National Museum of Natural History Geologic Time The Story of a Changing Earth
Presented by the Department of Paleobiology.
The Oligocene
Contents
Epoch Overview
Terrestrial Life Throughout the Oligocene
Oligocene Marine Life
Shifting Continents and Climates
Evidence
Skull of an entelodont
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sample
Three-toed horse
Camel
Oreodont
Saber-toothed cat
Saber-toothed cat
Extinct armored lizard
Tree oyster
references and links
Foundational Concepts
Dating Methods
Earth Processes
Life Processes
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Terrestrial Life Throughout the Oligocene
Drier climates in the interior of North America led to fewer sites where plant fossils were preserved, but there is some evidence for more open forests. Grasslands may have developed in some areas but were probably not widespread. Along the west coast of North America, relatively diverse forests of broad-leaved trees and conifers were common. In higher northern latitudes, forests consisted of broad-leaved deciduous trees and conifers.

Ungulates were remarkably diverse in the Oligocene. Among the even-toed forms (artiodactyls), oreodonts (imagine an animal with pig-like feet but molar teeth more like those of a cow) were very abundant in North America. Pig-like entelodonts roamed the continents alongside ruminants such as camels. Odd-toed ungulates (perissodactyls) included herds of three-toed horses and many forms of rhinoceros. These diverse Oligocene rhinos included agile running forms, and in Asia, the largest land mammals of all, the giant indricotheres. Carnivorans included early members of the dog and cat families, including saber-toothed cats. South America, which had been isolated from other continents for millions of years, developed a unique fauna that included edentates (armadillos and sloths), predatory marsupials (borhyaenids), and giant carnivorous ground birds (phorusrhacids).

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Overview | Terrestrial Life Throughout the Oligocene | Oligocene Marine Life
Shifting Continents and Climates



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