Indricotherium and Andrewsarchus

Indricotherium 

Central Asia

 34,000,000 - 23,000,000

 The Indricotherium (in-dri-co-fear-E-um) was bigger then an elephant and taller then a giraffe. Indricotherium was the largest land mammal to ever walk the earth, but it wasn't related to the elephant or giraffe, it was really a giant hornless rhinoceros. The easiest way to tell is that all rhinos have only three tows/fingers on each foot/hand, and like all rhinos they were odd towed ungulates (hoofed animals with an odd number of tows/fingers. Like the horse and modern rhino.)

The Indricotherium calf was only the size of a small adult rhino today and it is estimated that the calves were weened off their mothers milk after about a year. Like the modern rhino the Indricotherium most likely lived alone with the exception of mothers and their young.

Andrewsarchus 

 Mongolia

 45,000,000 - 36,000,000

 Andrewsarchus (An-drew-sar-cus) was a large carnivorous cloven-hoofed (even-towed ungulate) predator. Little is known about Andrewsarchus, manly because it is only known from the upper part of the skull and some other fragments.  It is believed that Andrewsarchus was a predator and scavenger (a little like the modern hyena) and most likely ate sea turtles, selfish, beached whales, (plants may have been included), and possibly stillborn brontotherium (bron-tow-fear-e-um) calves.

(Two Andrewsarchus' fighting over a dead brontotherium calf)

Andrewsarchus was the largest mammalian predator to ever live (Twice the size of the polar bear).  Andrewsarchus is known to be "a sheep in wolfs clothing" due to the fact that it's closest living relatives are sheep, goats, pigs, whales, and other cloven hooved animals.