Rise and rapid evolutionary development in grazing mammals and apelike creatures.
It is during this epoch that we see the first true apes and Old World monkeys. The Miocene was a time of great mammalian diversity, and many species originated and became extinct in response to environmental change. Although most of the Miocene apes were fruit-eaters (frugivorous), at least two species are thought to have been leaf-eaters (folivorous). The Miocene started out warmer than the preceding epoch. The warmth melted the polar ice cap that had formed over Antarctica. Fluctuating climate, which was characteristic of this epoch, caused a majority of the woodland environments to be replaced by savanna grasslands. These grasslands were home to a diverse fauna. In North America, species of rhino roamed the countryside alongside as many as a dozen horse species. Volcanic activity increased during the Miocene. Africa became more arid during this epoch, and India's collision with the Asian mainland continued to form the Himalayas. As South America moved north, the passageway between the continent and Antarctica opened up. The resulting circulation of cold waters around Antarctica led to the formation of deep, cold bottom waters in Earth's oceans.
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