Pebas Formation

The Pebas Formation is a lithostratigraphic unit of Miocene age, found in western Amazonia. The formation extends over 1000000 km2, including parts of Brazil, Peru, Ecuador and Colombia. It is interpreted as representing the deposits of a lake ("Lake Pebas") or series of lakes, formed within the foreland basin of the Andes mountain belt. It is known for its abundant fossil ostracods and molluscs and an unusually diverse group of crocodylians.