The Pliocene Epoch

5 to 1.8 mya

The picture below shows a modern herd of zebra grazing on an African savanna. Grazing mammals, such as members of the perissodactyl and artiodactyls diversified in the Miocene and Pliocene as grasslands and savanna spread across most continents.

The Pliocene was a time of global cooling after the warmer Miocene. The cooling and drying of the global environment may have contributed to the enormous spread of grasslands and savannas during this time. The change in vegetation undoubtedly was a major factor in the rise of long-legged grazers who came to live in these areas.

Additionally, the Panamanian land-bridge between North and South America appeared during the Pliocene, allowing migrations of plants and animals into new habitats. Of even greater impact was the accumulation of ice at the poles, which would lead to the extinction of most species living there, as well as the advance of glaciers and ice ages of the Late Pliocene and the following Pleistocene.