Both groups of modern ungulates (hoofed animals) became prevalent because of a major radiation between Europe and North America, along with carnivorous ungulates like "Mesonyx". Early forms of many other modern mammalian orders appeared, including bats, proboscidians (elephants), primates, rodents, and marsupials. Older primitive forms of mammals declined in variety and importance. Important Eocene land fauna fossil remains have been found in western North America, Europe, Patagonia, Egypt, and southeast Asia. Marine fauna are best known from South Asia and the southeast United States.