Here's some interesting news at Wildlife Extra.com about a new dwarf species of Amazonian Manatee discovered by Marc van Roosmalen.

The Amazonian manatee was thought to be the only manatee fully adapted to living in fresh water, until the discovery of the Dwarf manatee, Trichechus Bernardi, or Prince Bernhard’s dwarf manatee.

The story started in September 2002 when Marc van Roosmalen collected a skull of a recently killed adult male. He had to wait for 2 years until he found living proof of the Dwarf manatee, when he was able to study and film a live specimen that was kept in a corral in its natural environment for 4 months.
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Dwarf manatees are considered to be critically endangered as they are highly restricted ecologically and geographically. It is thought that there may be less than 100 individuals in this population, and they are not known from any other locality. They are hunted as game, and their habitat is highly susceptible to illegal mining of gravel and gold, timber extraction and commercial fishing.