JAKARTA, Indonesia —  Researchers in a remote jungle in Indonesia have discovered a giant rat and a tiny possum that are apparently new to science, underscoring the stunning biodiversity of the Southeast Asian nation, scientists said Monday.

Unearthing new species of mammals in the 21st century is considered very rare. The discoveries by a team of American and Indonesian scientists are being studied further to confirm their status.

The animals were found in the Foja mountains rainforest in eastern Papua province in a June expedition, said U.S.-based Conservation International, which organized the trip along with the Indonesian Institute of Science.

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"The giant rat is about five times the size of a typical city rat," said Kristofer Helgen, a scientist with the Smithsonian Institution in Washington. "With no fear of humans, it apparently came into the camp several times during the trip."

The possum was described as "one of the worlds smallest marsupials."

A 2006 expedition to the same stretch of jungle — dubbed by Conservation International as a "Lost World" because until then humans had rarely visited it — unearthed scores of exotic new species of palms, butterflies and palms.

Papua, otherwise known as the island of New Guinea, has some of the world's largest tracts of rainforest, but like elsewhere in Indonesia they are being ravaged by illegal logging.

Scientists said last year that the Foja area was not under immediate threat, largely because it was so remote.

"It's comforting to know that there is a place on Earth so isolated that it remains the absolute realm of wild nature," said expedition leader Bruce Beehler. "We were pleased to see that this little piece of Eden remains as pristine and enchanting as it was when we first visited."