The Columbian mammoth ("Mammuthus columbi") is an extinct species of mammoth that inhabited North America as far north as the northern United States and as far south as Costa Rica during the Pleistocene epoch. It was one of the last in a line of mammoth species, beginning with "Mammuthus subplanifrons" in the early Pliocene. DNA studies show that the Columbian mammoth was a hybrid species between woolly mammoths and another lineage descended from steppe mammoths; the hybridization happened more than 420,000 years ago. The pygmy mammoths of the Channel Islands of California evolved from Columbian mammoths. The closest extant relative of the Columbian and other mammoths is the Asian elephant.