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 is set at the start of the Pleistocene glaciations.
The Pliocene Faunal stages from youngest to oldest are:
Zanclian Piacenzian
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.