Miocene Epoch

Saturday, November 19, 2016

Miocene Epoch

The Miocene is the first geological epoch of the Neogene Period and extends from about 23.03 to 5.333 million years ago(Ma). The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words μείων (meiōn, “less”) and καινός(kainos, “new”) and means “less recent” because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene Epoch and is followed by the Pliocene Epoch.

The earth went from the Oligocene through the Miocene and into the Pliocene, with the climate slowly cooling towards a series of ice ages. The Miocene boundaries are not marked by a single distinct global event but consist rather of regional boundaries between the warmer Oligocene and the cooler Pliocene Epoch.

The apes arose and diversified during the Miocene, becoming widespread in the Old World. By the end of this epoch, the ancestors of humans had split away from the ancestors of the chimpanzees to follow their own evolutionary path. As in the Oligocene before it, grasslands continued to expand and forests to dwindle in extent. In the Miocene seas, kelp forests made their first appearance and soon became one of Earth’s most productive ecosystems. The plants and animals of the Miocene were fairly modern. Mammals and birds were well-established. Whales, seals, and kelp spread. The Miocene is of particular interest to geologists and palaeoclimatologists as major phases of the Himalayan orogeny had occurred during the Miocene, affecting monsoonal patterns in Asia, which were interlinked with glaciations in the northern hemisphere.

Prehistoric Life During the Miocene Epoch

Life during the Miocene Epoch was mostly supported by the two newly formed biomes, kelp forests and grasslands. This allows for more grazers, such as horses, rhinoceroses, and hippos. Ninety five percent of modern plants existed by the end of this epoch.

The “Middle Miocene disruption” refers to a wave of extinctions of terrestrial and aquatic life forms that occurred following the Miocene Climatic Optimum (18 to 16 Ma), around 14.8 to 14.5 million years ago, during the Langhian stage of the mid-Miocene. A major and permanent cooling step occurred between 14.8 and 14.1 Ma, associated with increased production of cold Antarctic deep waters and a major growth of the East Antarctic ice sheet. A Middle Miocene δ18O increase, that is, a relative increase in the heavier isotope of oxygen, has been noted in the Pacific, the Southern Ocean and the South Atlantic.