Like everywhere else, numerous animals in North America went extinct shortly after the end of the last Ice Age, about 12,000 years ago. Humans are thought to be the cause. Other animals went extinct millions of years earlier, during the Pleistocene. Many of these are large animals, and are referred to as megafauna. Little of the North American megafauna survives -- some examples include bears and American Bison. Of all the extinct animals from North America, most of them went extinct just as soon as humans were getting more numerous.
Some of the fascinating extinct animals that lived in North America include the American Lion, which is the largest subspecies of lion ever to have existed, and is 25% larger than the African lion (extinct 8000 BC); the Ancient Bison, which was the most numerous large herbivore for 8,000 years until it went extinct around 8000 BC; Cuvieronius, a large elephant with spiral tusks (extinct 7000 BC); the Dire Wolf, a large wolf that went extinct in 8000 BC; the Giant Beaver, with a length of up to 2.5 m (8.2 ft) that lived around the Great Lakes until 10,000 years ago; and the Giant Hutia, a rodent that could grow to the size of bears, which lived in Puerto Rico until just 3,000 years ago. Except for the Ancient Bison and the Dire Wolf, few of these extinct animals have living relatives.
There are many other extinct animals from North America. The Giant Short-Faced Bear, which is the largest bear that ever lived, standing at seven feet tall and ten feet long (extinct 10,500 BC); Glyptodon, an armadillo-like armored animal about the size of a VW Bug, which originally evolved in South America but moved to Texas; the famous saber-toothed tiger, which was a top predator in Pleistocene North America; the well-known Wooly Mammoth, with adaptations to Ice Age living, and is often found frozen in Canadian permafrost; and the American Cheetah, a cheetah-like animal more closely related to the modern Puma, and which is known only from bone fragments.
There are numerous other extinct animals from North America over its hundreds of millions of years of natural history, but this article just covered those that went extinct most recently.