Scientists said today they had found a "lost world" in an Indonesian mountain jungle that contained dozens of exotic new species of birds, butterflies, frogs and plants.
"It's as close to the Garden of Eden as you're going to find on Earth," said Bruce Beehler, co-leader of the US, Indonesian, and Australian expedition to part of the Foja mountains in the west of New Guinea.
Indigenous peoples living near the Foja range, which rises to 2,200 metres (7,218 feet), said they did not venture into the trackless area of 3,000 square kilometres (1,200 square miles) - roughly the size of Luxembourg.
The team of 25 scientists rode helicopters to boggy clearings in the pristine zone. "We just scratched the surface," Mr Beehler said. "Anyone who goes there will come back with a mystery."
An undescribed species and a long-beaked echidna
The expedition found a new type of honeyeater bird with a bright orange patch on its face, known only to local people.
They also found more than 20 new species of frog, four new species of butterfly and plants, including five new palms.
The team also took the first photographs of "Berlepsch's six-wired bird of paradise", which appears in 19th-century collections but whose home had previously been unknown.
The bird is named after six fine feathers about 10cm long on the head of the male
that can be raised and shaken in courtship displays.
The expedition also took the first photographs of a Golden-fronted bowerbird in front of a bower made of sticks, while he was hanging up blue forest berries to attract females.
Scientists also found a rare tree kangaroo, previously unsighted in Indonesia.
Mr Beehler said the naturalists reckoned that there was likely to be a new species of kangaroo living higher altitudes.
The scientists visited in the wet season, which limited the numbers of flying insects. "Any expedition visiting in the dry season would probably discover many more butterflies," he said.
Mr Beehler, who works at Conservation International in Washington, said the area was probably the largest pristine tropical forest in Asia. Animals there were unafraid of humans.
"I suspect there are some areas like this in Africa, and am sure that there are similar places in South America," he said.
Around the world, pristine areas are under increasing threat from expanding human settlements and pollution.
Mr Beehler said the Indonesian government was doing the right thing by keeping the area off limits to most visitors, including loggers and mineral prospectors.
The scientists cut two trails about four kilometres long, leaving vast tracts still to be explored.