Mammoths were one of the largest land mammals of the Pleistocene. Numerous genera and species of conifers, mosses, flowering plants, insects, mollusks, birds, mammals and other species survive to modern times. Mammoths and mastodons, bison, sabre-tooths, giant ground sloths, and many other large mammals occupied N. America, Asia, and Europe. Native horses and camels inhabited the plains of North America. At the end of the Pleistocene, many of the species went extinct. During the Pleistocene, global cooling, or ice ages occured. Temperate zones were covered by glaciers during cool periods and uncovered during the warmer interglacial periods.