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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Oligocene Marine Life
Life in the Oligocene oceans looked increasingly familiar. Fossil pinnipeds (seals and sea lions) first appeared in the late Oligocene seas, looking much like their modern descendants. Whales had evolved into the two suborders present today, the toothed whales (odontocetes) and baleen whales (mysticetes). These marine mammals lived alongside sea cows and increasingly modern shark species. Bony fishes thrived as well.

Marine invertebrates, too, took on a more familiar appearance. In the warm tropical seas, carbonate shell reefs extended as far north as North Carolina. Similarly, coral reefs developed in the Southern Hemisphere as far south as northern New Zealand. Nummulitid foraminiferans were common, and the first irregular echinoids (sea urchins) were present. Other major invertebrate groups included cephalopods (squid and octopus), bivalves, snails, and crustaceans.

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



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