Columbian mammoth
DNA has been sequenced from two Siberian mammoth molars (which judging by morphology belong to the steppe mammoth); at over a million years old, this is the oldest ancient DNA ever recovered. The two genomes recovered belong to separate and distinct lineages: one is ancestral to the woolly mammoth, the other is a previously-unknown lineage. The latter lineage hybridized with woolly mammoths at least 420,000 years ago, giving rise to the Columbian mammoth.