Miocene : Overview

Skull of Hemicyon
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Chalicothere
Three-toed horse
Dog
Primitive baleen whale
Giant-toothed white shark
Seal
Shark-toothed whale
Snail
Oak

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OVERVIEW

Miocene 23–5.3 mya

Defining Characteristics:

• half of marine invertebrates species are extant forms
• uplift of land separates Tethys Ocean from Indian Ocean
• ocean circulation changes to form major gyres (circles) in N & S hemispheres
• more seasonal climates in N. Hemisphere
• Map of the Miocene World

Secondary Characteristics:

• horses and even-toed herbivorous mammals diversify
• whales, seals, sea lions, and walruses diversify

This epoch was named Miocene by Charles Lyell in 1833 for strata at various European localities. He based this name on his observation that about one-fifth of the mollusk species found in these sediments represented living species. The name Miocene is derived from the Greek words meion (meaning “less”) and kainos (meaning “recent”), referring to the fact that fewer recent species were found in these rocks than in those of more recent age. Although Miocene-age rocks are known worldwide, many important sites are in North America, including Agate and Ashfall Fossil Beds National Monuments (Nebraska), Calvert Cliffs (Maryland), Buffalo Canyon and Stewart Valley (Nevada), and Lee Creek Mine (North Carolina).

The Miocene is one of the longest epochs of the Cenozoic Era and therefore forms a substantial part of the Neogene. It is most noted for the formation of wide expanses of open grassland across North America and Eurasia. These open habitats were home to a diversity of new forms of mammals; in particular, horses, rhinoceros, camels, and antelope-like mammals were common throughout North America. In the seas, great changes in ocean circulation encouraged the evolution and spread of marine vertebrates, including a great diversity of whales, seals, and sea lions. Distinct continental faunas were characteristic of this period, but so were migrations between many of the landmasses.

Epoch Overview | Terrestrial Life Throughout the Miocene | Miocene Marine Life
Shifting Continents and Changing Climates

Department of Paleobiology Home | National Museum of Natural History Home
Smithsonian Institution Home

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Tertiary Period

A unit of geologic time, which began about 65.5 million years ago and ended about 1.8 million years ago. The Tertiary comprises five epochs: Paleocene, Eocene, Oligocene, Miocene, and Pliocene. Together with the Quaternary Period it constitutes the Cenozoic Era.

grassland

A region where grass is the dominant vegetation

mammal

Any member of the vertebrate class Mammalia. Mammals are distinguished by having hair, specialized teeth, separate air and food passages, a complex brain, and a constant, self-regulated, warm body temperature. Females have milk glands and give birth to living young.

horse

Any member of the perissodactyl ungulate family Equidae.

epoch

The fourth largest division of the geologic time scale, subdivision of a period. The Paleogene Period (part of the Cenozoic Era) is divided into the Paleocene and Eocene epochs. Epochs may be divided into ages.

rhinoceros

Any member of the mammalian family Rhinocerotidae, which are odd-toed ungulates. Rhinoceroses were quite diverse through much of the mid-Cenozoic, although there are only five living species.

Paleogene Period

The first of the two periods of the Cenozoic Era; it lasted from 65.5 to 33.9 million years ago.

Neogene Period

The second of the two periods of the Cenozoic Era; it lasted from 33.9 to the present.