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 slightly uncertain. The Pliocene was named by Sir Charles Lyell. It means roughly "continuation of recent" and refers to the essentially modern mammalian faunas.
The Pliocene boundaries are not set at an easily identified worldwide event but rather at regional boundaries between the warmer Miocene and the relatively cooler Pliocene. The upper boundary was intended to be set at the start of the Pleistocene glaciations but is now considered to be set too late.
The Pliocene Faunal stages from youngest to oldest are:
Continents continued to drift toward their present positions. South America became linked to North America through the Isthmus of Panama bringing a nearly complete end to South America's distinctive marsupial faunus. Climates became even cooler eventually leading to the Pleistocene glaciations. Pliocene rocks are well exposed in the Mediterranean, India, and China.
Both marine and continental faunas were essentially modern. The first recognizable primitive humans appeared in the late Pliocene.