The Channel Islands mammoth, under 5 feet 8 inches tall, is a case of island dwarfism. Stranded on the islands as sea levels rose at the end of the ice age, Columbian mammoths adapted to shrinking resources by shrinking in size. These small mammoths survived until thirteen thousand years ago when humans arrived.
The mammoth and the mastodon are both proboscideans— mammals with trunks. The mastodon looked more like the Asian elephant but with cusp-shaped teeth. Mastodons lived in herds and browsed in forests throughout North America. They left their bones in the ground as part of a mass extinction thought to be caused by the Clovis people hunting and killing them ten to eleven thousand years ago.
Two and a half times the size of the surviving nine-banded armadillo, the beautiful armadillo is morphologically similar. Thousands of bony scutes covered its body. Fossils of these scutes, called osteoderms, are the most common remains of the beautiful armadillo in caves, sinkholes, and river or lake deposits.
The camelops is a true camel related to the Old World dromedary and the Bactrian camel and is distantly related to the alpaca, guanaco, llama, and vicuña. They say that all camels originated in North America four million years ago, and spread to Eurasia across the Bering Strait. Like mastodons, ground sloths, and giant beavers, they were extirpated about eleven thousand years ago.
Somewhat larger than a modern wolf and with a longer tail, the dire wolf is a carnivore that preyed on camels, horses, ground sloths, mastodons, and bison. They probably hunted these large herbivores in packs like modern wolves and disappeared along with their prey after humans arrived in North America.
This robust cat with long canine teeth was not related to the lion, tiger, or puma. Little is known of its behaviors other than it preyed on large herbivores. Hundreds of its skeletons have been found trapped in the La Brea tar pits along with dire wolves, short-faced bears, Pleistocene mammoths, mastodons, pronghorn antelopes, camelops, elk, shrub-oxen, llamas, and sheep, dogs, coyotes, gray wolves, bobcats, skunks, weasels, foxes, raccoons, cougars, cheetahs, American lions, badgers, and bats, mule deer, bighorn sheep, peccaries, ground sloths, pigeons, doves, bitterns, mallards, geese, swans, and storks, falcons, hawks, eagles, and vultures, bluebirds, robins, herons, egrets, spoonbills, ibis, grebes, and woodpeckers, owls, sparrows, jays, goldfinches, ravens, kestrels, quails, turkeys, cranes, and coots, bison, horses, jackrabbits, rats, chipmunks, voles, mice, squirrels, shrews, and gophers along with reptiles and invertebrates ten to twenty thousand years ago.
Ursus arctos horribilis of Aridoamerica, likely unrelated to the California grizzly, was an omnivore, eating plants, fruit, ants, small animals, and cattle, for which it was trapped, shot, and poisoned, even after, eventually, being legally protected.