There is a small family of cetaceans known as Platanistidae. They are known, in English, as river or beaked dolphins because they all inhabit fresh water and have long, narrow, toothed beaks. But they are not Delphinoidea, they are much more closely related to Beaked whales and Sperm whales than to dolphins, and link to some of the oldest fossil groups of whales.
One of these river dolphins lives in India, one around the Amazon, and one, which I've had the privilege of encountering, lives in the Rio de la Plata and some other rivers in Argentina, Uruguay and Brazil.
The fourth one was restricted to the mainstream of the lower and middle reaches of the Yangzi-jiang River below the Three Gorges, central China; and in neighbouring tribuatries and the outlet of Dongting Hu.
In the 80's, little was known about it and scientiests of the Wuhan Institute of Hydrobiology were studying it. At the time, some concern was felt for their future and local scientists were seeing how they could best be protected. They were caught on fisherman's lines and valued for the medicinal qualities of their meat and fat, although not heavily hunted.
A more recent study has been done on these delightful little (1.5 - 2.5 m) dolphins. On 8 August 2007 they were officially declared extinct.
In spite of humanity's best efforts, these are the first cetaceans we have completely wiped out. I doubt that they will be the last.
Next time you snap up a bargain,'made in China', remind yourself of its real price.
Well done, Homo Sapiens.