Volcanism and fragmentation of western North America is associated with the emplacement of major ore deposits. The climate is generally temperate. Glaciation begins in Antarctica. Representatives of modern mammals become the dominant vertebrate life form, including horses, pigs, true carnivores, rhinoceroses, elephants, and camels. Oreodonts diversify in North America.
Early primates appear in North America, and early apes appear in Egypt.
Many archaic mammals become extinct. The world's oceans teem with more diverse vertebrate life. Grasslands expand, and forest regions diminish. Miocene Epoch 24-5 million years ago Modern ocean currents are essentially established. A drop in sea level isolates and dries up the Mediterranean Sea, leaving evaporite deposits on its floor.