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The Miocene epoch, 23-5 million years ago, saw the emergence of grasslands, separation of Antarctica from South America, and evolution of modern mammals. Hardwood forests retreated, giving rise to herbivorous species and megafauna. The era also saw the evolution of echolocation and the emergence of great apes and intelligent precursors of Homo.
The Miocene epoch encompasses the period between 23 and 5 million years ago on Earth. Means “older” in Greek, a reference to the fact that the type and distribution of marine invertebrates during the period varied substantially from that of the more recent period, 5 million years ago to the present. Otherwise, there are many similarities between the Miocene epoch and the present day (the Holocene). The Miocene epoch is the first epoch of the Neogene period, which began 23 million years ago and continues to the present day. The Neogene period was preceded by the Paleogene.
The Miocene epoch marked the beginning of the world’s great grasslands, which aggressively covered the land left behind by dying forests. The first significant planetary event to occur during the Miocene epoch was the separation of Antarctica from South America, creating Drake’s Passage and allowing for the freezing Antarctic Circumpolar Current. This caused Antarctica, which had been a temperate forest climate during the preceding Paleogene period, to become covered in mile-thick glaciers. The climatic influence of Antarctica has cooled the entire planet to some extent.
Many modern mammal groups were evolving significantly during the Miocene epoch, including the felids, which emerged shortly before the period began, and modern-looking dogs, although canids had evolved over 16 million years earlier . Ursids (bears) and canids existed about 39 million years ago, but it was not until the early Miocene that they migrated from North America to Eurasia and Africa. Echolocation evolved during the Miocene, allowing whales and dolphins to observe the aquatic environment with an instrument beyond sight. Primates started the era in a relatively primitive state. The apes split from the Old World monkeys about 23 million years ago. They evolved into great apes 18 million years ago, and intelligent precursors of the genus Homo existed 5 million years ago. Australopithecus afarensis, one of the first major leaps forward from the great apes and to mankind, didn’t evolve until about 3.7 million years ago.
Hardwood forests, which previously existed up to 45 degrees away from the equator (including most of present-day Eurasia and the United States), retreated to just 20 degrees away from the equator during the Miocene epoch. This has caused an evolutionary shift from tree species to herbivorous species. Many of the key mammals have grown significantly in size, giving rise to megafauna such as elephants. In general, the Miocene can be thought of as the Age of Herbs, a circumstance that had never occurred before in the history of the Earth. Grasses only evolved about 80 million years ago and didn’t dominate the planet until the Miocene.
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