Smithsonian National Museum of Natural History Geologic Time The Story of a Changing Earth
Presented by the Department of Paleobiology.
The Pliocene
Life in the Pliocene
Tectonics during the Pliocene
Climate Cycles during the Pliocene
Ostracode, a member of a group of crustaceans
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Pliocene 5.3 - 1.8 mya
Defining Characteristics:
  • • continuation of “Age of mammals”
  • • appearance of early bipedal ancestors of humans
  • • Great American Interchange
Secondary Characteristics:
  • • expansion of grasslands
  • • beginning of separation between Atlantic and Pacific marine organisms

The Pliocene is the final epoch of the Neogene Period. It was named by Charles Lyell in 1830, after the Greek words pleion (meaning “more”) and kainos (meaning “recent”). The Pliocene represents the beginning of the familiar modern faunas; many of the plants and animals from that time have continued to live and evolve to the present day. Indeed, Lyell devised the name because he noticed that of all the Cenozoic marine fossils, those from Pliocene strata were the most similar to modern forms. This characteristic distinguished these layers from earlier Miocene or Eocene strata.

During this part of the Age of Mammals, the global climate underwent cyclic variations from cool and dry to warm and wet, then back to cool conditions again. Pliocene aquatic fossils are numerous, and they range from tropical marine life to freshwater fish and invertebrates. They have been found in many places around the world, including Ahl al Oughlam (Morocco), Bodjong (Indonesia), and the Salada Formation (Mexico). Dry, open grasslands and savannas were prevalent on land. Plants very similar to those in modern forests occupied river valleys and other habitats. In North America, abundant fossils of mastodons, mammoths, and three-toed horses have been found in Kettleman Hills (California), Hemphill Beds (Texas), and the Hagerman Fossil Beds National Monument (Idaho).


Overview | Life in the Pliocene | Tectonics during the Pliocene
Climate Cycles during the Pliocene

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