Miocene

The Miocene is a geological epoch of the Neogene period and extends from about 23.03 to 5.33 million years before the present. As with other older geologic periods, the rock beds that define the start and end are well identified but the exact dates of the start and end of the period are uncertain. 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 of modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene Epoch and is followed by the Pliocene Epoch. The Miocene is the first epoch of the Neogene Period.

As the earth cooled, it went from the Oligocene epoch through the Miocene and into the Pliocene. The Miocene boundaries are not set at an easily identified worldwide event but rather at regional boundaries between the warmer Oligocene and the cooler Pliocene.

The plants and animals of the Miocene were fairly modern. Mammals and birds were well-established. Whales, seals, and kelp spread.