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
Two Forms (Divided Circle) "Maquette for Divided Circle", cast in polished bronze. Two Forms (Divided Circle) Two Forms (Divided Circle) (BH 477) is a bronze sculpture by Barbara Hepworth, designed in 1969. Six numbered copies were cast, plus one (0/6) retained by the sculptor. The sculpture's dimensions are by by . The front of the base has "Barbara Hepworth 1969" inscribed on it followed by the number of the sculpture, as well as "Morris | Singer | FOUNDERS | LONDON", both inscribed by casting. The sculpture is considered to be one of Britain's most recognisable works. The sculpture is late work by Hepworth, created