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Pliocene

The Pliocene epoch is the period in the geologic timescale that extends from about 5 million to 1.8-1.6 million years before present.

The Pliocene follows the Miocene epoch and is followed by the Pleistocene epoch. The Pliocene is the fifth and last epoch of the Tertiary Era.

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 epoch are slightly uncertain. The Pliocene was named by Sir Charles Lyell. The name 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:

  1. Zanclian
  2. Piacenzian

Continents continued to drift toward their present positions, moving from positions possibly as far as 250km from their present locations to positions only 70 km from their current locations. South America became linked to North America through the Isthmus of Panama[?] during the Pliocene, bringing a nearly complete end to South America's distinctive marsupial faunas. Climates became even cooler. Antarctica became ice-bound near or before the start of the Pliocene. Mid-latitude glaciations were probably underway before the end of the epoch. Pliocene marine rocks are well exposed in the Mediterranean, India, and China. Elsewhere, they are exposed largely near shores.

Both marine and continental faunas were essentially modern, although continental faunas were recognizably a bit more primitive than today. The first recognizable primitive humanoid ancestors appeared in the late Pliocene.



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