Miocene

The Miocene (/ˈmaɪ.əsiːn, -oʊ-/ MY-ə-seen, -⁠oh-)^[6][7] was the first geological epoch of the Neogene Period (the second geologic period of the Cenozoic Era), extending from about 23.03 to 5.333 million years ago (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words μείων (meíōn, "less") and καινός (kainós, "new"),^[8][9] meaning "less-recent" as it contained 18% fewer modern marine invertebrates than the Pliocene.^[10] The Miocene was preceded by the Oligocene and was followed by the Pliocene.

As Earth shifted from the Oligocene, through the Miocene, and into the Pliocene, the climate slowly cooled towards a series of ice ages.^[11][12] The Miocene boundaries are not marked by a single or distinct global event, but rather consist of regionally-defined boundaries between the warmer Oligocene and the cooler Pliocene Epochs.

During the Early Miocene, Afro-Arabia collided with Eurasia, severing the connection between the Mediterranean Sea and Indian Ocean, thus facilitating a biotic interchange between all the aforementioned landmasses and continents; this included the dispersal of proboscideans into Eurasia from Africa. During the late Miocene, the connections between the Atlantic and Mediterranean closed, causing the Mediterranean to nearly completely evaporate, in an event called the Messinian salinity crisis. The Strait of Gibraltar later formed at the Miocene-Pliocene boundary, initiating a dramatic event known as the Zanclean flood, in which the Mediterranean Sea was reopened to the Atlantic Ocean—subsequently allowing it to be refilled with infinite amounts of seawater.

The apes first evolved and diversified during the early Miocene (Aquitanian and Burdigalian Stages), becoming widespread in the Old World. By the end of this epoch, and the start of the following one, the ancestors of humans had split away from the ancestors of the chimpanzees to follow their own evolutionary path during the final Messinian Stage (7.5–5.3 Ma) of the Miocene. As during the Oligocene before, grasslands continued to expand, and forests to dwindle, in extent. In the seas of the Miocene, kelp forests made their first appearances and soon became one of Earth's most productive coastal marine ecosystems.^[13]

The flora and fauna of the Miocene were recognizably modern. Mammals, birds, herpetofauna and the fishes were well-established; cetaceans, pinnipeds, and the aforementioned kelp developed and spread.

The Miocene is of particular interest to geologists and palaeoclimatologists, as major phases of the geology of the Himalaya occurred during the Miocene, affecting monsoonal patterns in Asia, which were interlinked with glacial periods in the Northern Hemisphere.^[14]