Eocene

Eocene is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name Eocene comes from the Ancient Greek ηώς (ēṓs, "dawn") and καινός (kainós, "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch.

Overview

The Eocene follows the Paleocene Epoch and is followed by the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. The end is set at a major extinction event called the Grande Coupure (the "Great Break" in continuity), which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay. As with other geologic periods, the strata that define the start and end of the epoch are well identified, though their exact dates are slightly uncertain.

Climate

The Eocene was a time of warming. At the start of the Eocene, the high temperatures and warm oceans created a moist, balmy environment, with forests spreading throughout the Earth from pole to pole. Polar forests were quite extensive. Later during the Eocene, the continents began to drift toward their present positions. Antarctica, which began the Eocene fringed with a warm temperate to sub-tropical rainforest, became isolated and over the course of the Eocene developed a much colder, less humid climate.

Flora and Fauna

The Eocene epoch contained a wide variety of different types of animals and plants. During this time, the first mammals appeared, including early primates and odd-toed and even-toed ungulates. The evolution of the horse, a significant event in mammalian evolution, occurred in the early Eocene. Birds also evolved substantially in the Eocene.

See Also

• Paleocene
• Oligocene
• Cenozoic Era
• Geological Epoch
• Horse Evolution

References

Eocene Resources
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