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
Two Forms (Divided Circle) 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 only 6 years before her death in a