EoceneEocene

Eocene

The Eocene epoch is a geologic epoch spanning from 56 to 34 million years ago. It is the first epoch of the Paleogene period and is preceded by the Paleocene epoch. The Eocene is divided into three subdivisions: the Priabonian, Bartonian, and Lutetian.

During the Eocene, the Earth's temperature was higher than it is today and polar ice caps had begun to form and then melt, sometimes multiple times. Forests and deserts expanded and contracted according to changes in climate. Great rivers may have flowed across the Arctic Circle and shallow seas covered much of North America, Europe, and Asia.

A key characteristic of the Eocene is the rapid evolution of mammals, particularly primates, rodents, and ungulates. Many of these species gave rise to modern mammalian families, and some mammals became more specialized during this time. Marine mammals, such as cetaceans and dugongs, emerged during the Eocene. The first modern species of whales appeared in the Eocene, including Pakicetus and Basilosaurus.

Fossils of plants and animals from the Eocene have been found in many parts of the world. Beaches in Greenland yield well-preserved Eocene fossils, while the American Phosphate region, as well as Australia, have also provided many fossil discoveries. Some Eocene sedimentary rocks have been found to contain beds rich in coal and phosphate, as well as deposits of sedimentary iron ore.