any member of an extinct group of large-hoofed mammals (mammal) that originated in Asia or North America during the early Eocene Epoch (some 50 million years ago). Titanotheres, more properly called “brontotheres (brontothere),” became extinct during the middle of the Oligocene Epoch (some 28 million years ago). Most were large and fed mainly on soft vegetation. Their skulls were massive and frequently adorned with large bony protuberances covered in skin that may have been used in intraspecific combat or as defensive weapons against predators. The bodies were bulky with strong, pillarlike limbs. The remains of titanotheres are abundant in the geologic record, and the different forms must have been locally numerous; it is possible that they moved about in herds.