CREDIT: KENNETH B. TANKERSLEY Ph.D If we had a machine that could take us back to the time of Paleoindians, the view would be unlike anywhere found in the world today. We would experience warmer winters and cooler summers, but they would be extremely erratic from one year to the next. We would see a mosaic of plant and animal communities, parklands of spruce and pine, open patches of grassland interrupted by an occasional cedar, and shallow streams and wetlands bounded by willows and poplars. The waters would be filled with the same variety of fish and turtles, frogs and salamanders, and snakes that we see today. In the sky, we would find the same ducks and geese, hawks and owls, and vultures and eagles, and even bats flying at night. The woodlands would be filled with chipmunks and squirrels, porcupines and woodchucks, mice and voles, deer and elk, and an occasional black bear, along with caribou, pine martins and fishers, mink and ermines, and even tiny animals, called micromammals, such as northern bog lemmings, and the mountain-heather, boreal redback, and yellow-cheeked voles. Among this modern menagerie of animals, we would also see strange, giant creatures known as megamammals walking, swimming, and flying across the landscape. We would see two very different herds of hairy elephants (the Wooly and Jefferson mammoths) grazing on grasses and riverside willows. They would tower over the hairy elephant-like mastodon, giant deer-like stag-moose, and tapirs browsing in and around the bogs and fens. In the deeper water, we would see bear-sized beaver-like creatures, swimming with cattails and rushes in their mouths. In the nearby parklands, we would find two kinds of giant ground slothís (the Jefferson and Harlanís) standing on their hind legs, as tall as the trees they bow with their giant claws, browsing on tender green leaves. At salt springs, we would see herds of colossal-sized complex-toothed horses, giant bison, and huge, hairy woodland muskoxen grazing on prairie grasses. In the distance, we would see herds of two kinds of giant hairy pig-like creatures (the long-nosed and flat-headed peccaries). Packs of dire wolves and a short-faced bear would be keeping a watchful eye on the young and weak, as California condors circle overhead waiting for their next meal. This seemingly idyllic American Serengeti was vulnerable to change. Climate at the end of the last Ice Age was like a flickering candle flame, unstable, rapidly changing, and, finally, coming to an end. Not every plant or animal had the same tolerance to this profound climatic change. Some plants and animals were unaffected, remaining in their homeland, others moved north, south, east, or west, some became smaller in size, but more than thirty species could neither adapt nor moveóthey became extinct. In this changing climate, Paleoindians explored virtually all types of environmental and topographic settings with a mobility that was greater than that any modern hunter-gatherer. They created a variety of sites including megamammal kill and scavenging sites, stone quarries, workshops, base camps, short-term camps, burials, caches, and a seemingly infinite number of more limited activity areas. The low density of artifacts at these sites suggests that Paleoindian population was sparse. Campsites contain no evidence for formal houses and little refuse or features such as pits and fireplaces. Paleoindian technology was portable and the individuals that used them likely manufactured most weapons and tools. They did not live in isolation. Contact between groups occupying neighboring areas would have been necessary to maintain an open exchange of information, raw material, and marriage partners. Our only possible indication of exchange is the presence of artifacts manufactured from exotic rocks and minerals. Caches of these materials were buried at strategic locations. The vast majority of our knowledge about Paleoindians and the plants and animals that lived in America during the Ice Age is based on their artifacts and fossil remains that have been discovered by amateurs, collectors, and advocationals from plowed fields, sand and gravel pits, peat bogs and ponds, and deeply buried cave passages. By directly radiocarbon dating artifacts, plant and animal fossils, and plotting where they were found on maps, we can glean important clues about Paleoindian cultures and the Ice Age environment.