TITANOTHERE

any member of an extinct group of large-hoofed mammals that originated in North America during the Early Eocene Epoch (from 57.8 to 52 million years ago) and were present in North America and Asia during the Oligocene Epoch (which occurred from 36.6 to 23.7 million years ago). They became extinct during the middle Oligocene. Most were large forms that fed mainly on soft vegetation. The skulls were massive and frequently adorned with large horns that were probably effective battering rams in combat with other titanotheres, perhaps between males for territorial dominance, or as defensive weapons against predators. The bodies were bulky, the limbs pillarlike and strong, and the brain very small and primitive. The remains of titanotheres are abundant in the geologic record, and the different forms must have been locally numerous; it is possible that the titanotheres moved about in herds. They probably became extinct because their relatively simple dentition could not effectively cope with the high silica content of the grasses that were spreading during the Oligocene Epoch.