What is the X in X-mas?
A very large, extinct land mammal of the genus Indricotherium (formerly Baluchitherium) of the Oligocene and Miocene Epochs. It stood 5.5 m (18 ft) high at the shoulder and weighed four times as much as an elephant. It was related to the rhinoceros but had a long neck, long legs, and no horns. The indricotherium is the largest land mammal known to have existed.