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
Smooth-toothed pocket gopher move the traps. Toxic bait can also be used, but involves a different trap placement strategy. Fumigation is usually unsuccessful because gophers can quickly seal off their burrows at the first whiff of fumes. The exception to this is fumigation with aluminum phosphide; however, this can only be used by a professional. Gas explosives and flooding have commonly been utilized to force gophers from their burrows, and while sometimes successful, are not guaranteed to achieve full eradication. Smooth-toothed pocket gopher The smooth-toothed pocket gophers, genus Thomomys, are so called because they are among the only pocket gophers without grooves on