Pleistocene (Pleistocene) - epoch, which began 2,588 million years ago and ended 11,700 years ago. It is preceded by the Pliocene epoch, and is a follower of the Holocene epoch. The Pleistocene fauna of North America included: giant sloths (Megatherium), flat-faced bears (Arctodus simus), California tapirs, peccaries, American lion (Panthera (Leo) atrox), a giant jaguar (Panthera onca augusta), a giant condor, Miracinonyx, saber-toothed cats (Smilodon fatalis), (Homotherium), an "awful" wolf (Canis dirus), two species of bison, Tylopoda, horses, mammoths (Mammuthus columbi), (Mammuthus primigenius) and Mammutidae (Mammut americanum), giant beavers, as well as birds like Teratornis. Currently, the largest animal in North America - the bison. Most of the megafauna that existed in the late Pleistocene, died. t is assumed that the extinction caused new diseases or primitive hunters, or it was a result of climate change or a combination of all factors.