The first tapiroids, such as "Heptodon", appeared in the early Eocene of North America. They appeared very similar to modern forms, but were about half the size, and lacked the proboscis. The first true tapirs appeared in the Oligocene. By the Miocene, such genera as "Miotapirus" were almost indistinguishable from the extant species. Asian and American tapirs were believed to have diverged around 20 to 30 million years ago; tapirs later migrated from North America to South America around 3 million years ago, as part of the Great American Interchange. For much of their history, tapirs were spread across the Northern Hemisphere, where they became extinct as recently as 10,000 years ago. "T. merriami", "T. veroensis", "T. copei", and "T. californicus" became extinct during the Pleistocene in North America. The giant tapir survived until about 4,000 years ago in China.