Platanistoidea

Platanistoidea (order Cetacea, suborder Odontoceti) A superfamily that comprises the one family Platinistidae (river dolphins), cetaceans which are believed to be related closely to the squalodonts (Squalodontoidea) and to forms known from the early Miocene, and to be more primitive than other Odon-toceti. The temporal opening is unroofed. The beak is long and slender, the teeth peg-like and vary in number according to species. The cervical vertebrae are not fused, and the neck is distinct. The flippers are broad and short, the dorsal fin low, and the tail slightly notched at the mid-line. River dolphins grow to a length of 1.5–2.9 m. There are five species in four genera. Platanista, which is blind, is found in the Indus, Ganges, and Brahmaputra rivers of India, and there are two species; Inia inhabits the Amazon and upper Orinoco rivers of S. America; Pontoporia is found in the estuary of the La Plata river, and along the south-east coast of S. America; Lipotes is found only in Lake Dongting, on the Changtze Jiang river, in China.