Miocene
The Miocene is the last and final epoch of the first Neogene period and the fourth of the Cainozoic. It started about 23 million years ago and ended about 5.33 million years ago. The rock beds that mark the start and end are well known, but the exact dates of the start and end of the period are uncertain. The Miocene was named by Charles Lyell. The name comes from the Greek words  (, “less”) and  (, “new”) and means "less recent", because it has 18% fewer modern sea invertebrates than the Pliocene.