Toothed whale porpoise as a fish. Toothed whales, as well as baleen whales, are descendants of land-dwelling mammals of the artiodactyl order (even-toed ungulates). They are closely related to the hippopotamus, sharing a common ancestor that lived around 54 million years ago (mya). The primitive cetaceans, or archaeocetes, first took to the sea approximately 49 mya and became fully aquatic by 5–10 million years later. The adaptation of echolocation and enhanced fat synthesis in blubber occurred when toothed whales split apart from baleen whales, and distinguishes modern toothed whales from fully aquatic archaeocetes. This happened around 34 mya. Unlike toothed whales, baleen
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