Evolution of cetaceans "Caperea marginata") all have derived characteristics presently unknown in any cetothere and vice versa (such as a sagittal crest). The adaptation of echolocation occurred when toothed whales (Odontoceti) split apart from baleen whales, and distinguishes modern toothed whales from fully aquatic archaeocetes. This happened around 34 million years ago in a second cetacean radiation. Modern toothed whales do not rely on their sense of sight, but rather on their sonar to hunt prey. Echolocation also allowed toothed whales to dive deeper in search of food, with light no longer necessary for navigation, which opened up new food sources. Toothed whales
Flat-spired three-toothed snail among 40 species of tridopsine snails in eastern North America. Populations were divided into family trees showing the phylogenetic relationships among 18 groups of species. Nine of these groups consisted of a single species, of which "Triodopsis platysayoides" was one group. This species of snail is endemic to the United States. The flat-spired three-toothed snail is found only in West Virginia, among Upper Connoquenessing sandstone outcroppings and boulders, in a restricted area along the rim of the Cheat River gorge. The U.S. Fish and Wildlife Service considers this snail to be threatened since 1978. Little is known about the life