Figure 32.29 Diversity among the Eutherians (A) The North American beaver exhibits the gnawing teeth that characterize rodents. Almost half of all eutherians are rodents. (B) Flight evolved in the ancestor of bats. This Townsend’s big-eared bat uses its enlarged ears to detect insect prey by echolocation. (C) Large hoofed mammals such as giraffes, zebras, and springboks are major herbivores of grasslands and savannahs. (D) Bottle nosed dolphins are cetaceans, a cetartiodactyl group that returned to the marine environment.