Date: Oligocene Epoch (34-23 million years old)
Description: Oreodonts were sheep-sized herbivore mammals that looked similar to modern pigs, but behaved more like modern camels. They were cud-chewing animals with four hooves and long tails. The name “oreodont” means “mountain teeth,” and these animals are so-called because their teeth had molars. Using these molars, oreodonts ate grass and low vegetation, rather than our modern pigs, which are omnivorous. They were herd animals and were thought to live all over the Midwest, though fossils are most commonly found in Nebraska, western South Dakota, and Wyoming. They were the main prey of saber-tooth tigers and bear dogs that were the major predators of this region at the time.
Donor: Sioux City Academy of Science and Letters.