The Paraceratherium, the humongous rhinoceros cousin formerly known as Indricotherium or Baluchitherium, once roamed the deserts of Asia during the Oligocene Epoch (34-23 million years ago). If it had survived to the days of recorded history, perhaps the Persian Empire would have found it handy as a battle mount. They certainly could have crushed all 300 of those pesky Spartans with a few of those magnificent beasties!