The Barzalosa Formation (Spanish: Formación Barzalosa, Pgb, Pgba) is a fossiliferous geological formation of the and the bounding foothills of the Central Ranges and Eastern Ranges of the Colombian Andes. The formation consists of conglomerates, sandstones and siltstones. The Barzalosa Formation probably dates to the Late Paleogene to Early Neogene period; Oligocene to Early Miocene epochs, and has an approximate thickness of 360 metres (1,180 ft). Fossils of Balanerodus logimus, , Xenastrapotherium chaparralensis, Protheosodon sp. and Proadinotherium sp. have been uncovered from the formation in Chaparral, Tolima.