Miocene

Part of speech: noun

Definitions

1. A geological time period spanning roughly 23 to 5 million years ago, marked by significant evolutionary and climatic changes
2. An epoch in Earth’s history lasting from around 23 million to 5 million years before the present, known for important developments in flora and fauna
3. A division of geological time occurring between about 23 and 5 million years ago, characterized by the evolution and spread of many modern plant and animal groups

Etymology: The Miocene is named for a proportion. In 1831 the English polymath William Whewell coined it from Ancient Greek "meíōn" ("less") and "kainós" ("new"), and the name was meant to measure how many living species in the rock record were still alive today. Whewell's idea was that the fossil faunas of this epoch contained fewer modern species than those of the epochs that followed, so the epoch was "less new" than the Pliocene and Pleistocene that came after it. The geologist Charles Lyell adopted the term and introduced it to the public in 1833, in volume III of his "Principles of Geology." Lyell had been working out a scheme for dividing the Tertiary rocks by the percentage of shells that matched species still living, and Whewell's Greek coinage gave that scheme a name. The term has since been kept, even though the proportion it was built on was only a rough guide.

Synonyms: epoch, geological period