The Eocene Epoch

54.8 to 33.7 mya

The Eocene epoch is part of the Tertiary Period in the Cenozoic Era, and lasted from about 54.8 to 33.7 million years ago (mya). The oldest known fossils of most of the modern orders of mammals appear in a brief period during the Early Eocene and all were small, under 10 kg. Both groups of modern ungulates (Artiodactyla and Perissodactyla) became prevalent mammals at this time, due to a major radiation between Europe and North America.

Vivveravus, a small mongoose-like carnivore from the Eocene of North America.

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Subdivisions of the

The chart at left shows the major subdivisions of the Paleogene, the first portion of the Tertiary Period, including the Eocene. You may click anywhere on the other Epochs or the arrows to navigate to those exhibits.

The Eocene Epoch is part of the Cenozoic Era.

Find out more about the Tertiary paleontology and geology of North America at the Paleontology Portal.