Scientists believe they have found a new undocumented mammal -- a pygmy possum -- in the jungles of a remote mountain range in Indonesia's Papua province, a conservation group said. During an expedition to Papua's Foja Mountains in June, Conservation International (CI) and Indonesian scientists documented the Cercartetus pygmy possum, one of the world's smallest marsupials, and a Mallomys giant rat, the conservation group said in a statement. Both mammals are currently under study and are apparently new to science, it said. Scientists from the Indonesian Institute of Sciences and CI discovered dozens of new plants and animals on their first trip to the region, described as a "Lost World", in late 2005. The Foja Wilderness is part of the great Mamberamo Basin, the largest unroaded tropical forest in the Asia Pacific region. With 42 million hectares (104 million acres) of tropical forests and some of the richest bio-diversity in the world, Papua is considered the country's last rainforest frontier. But it is under threat from increased cutting and clearing for palm oil plantations as well as rampant illegal logging.