2 pages found in
Wildlife:
Chelus fimbriatus, by William H. Espenshade III, an article about these turtles. They occur in northern South America, including both the Orinoco River and Amazon River basins.
http://www.tortoise.org/archives/matamata.html
Chelus fimbriatus biology and captive requirements, by David T. Kirkpatrick.
http://www.unc.edu/~dtkirkpa/stuff/mata.html