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
Double-toothed barbet the seeds of some fruits. These barbets can be found in pairs or small family groups with helpers; lone double-toothed barbets are rare. Their territories are large. Double-toothed barbets roost communally, as all the barbets in a group roost in the same hole. Nests are made by excavating a tree, often rotting, at above two meters. Both barbets in a pair will dig out the nesting hole, and both will defend it. The entrance the nest is circular, five or more centimeters across. Some nests have an entrance tunnel. At maximum, a nest is 46 centimeters deep. When a male