Two marsupial species that scientists thought had gone extinct at least 6000 years ago have been found alive on the island of New Guinea.

The ring-tailed glider and pygmy long-fingered possum, previously known to science only from fossils found in Australia, have now been found and photographed in the Vogelkop peninsula in Papua, Indonesia, with the help of local Indigenous communities.

Tim Flannery at the Australian Museum in Sydney says it took him and his colleagues many years of detective work to confirm that the animals are, in fact, back from the dead, involving tantalising sightings, misidentified museum specimens and the recovery of sub-fossil remains.

Recent photographic evidence and close work with local communities have finally allowed researchers to confirm the animals are actually alive, but their habitat faces grave threats from logging. Scientists know little of their exact range and ecological needs, posing challenges for their conservation.

Scott Hucknull at Central Queensland University in Australia, who wasn’t part of the team, says the discoveries are “more important than finding a living thylacine in Tasmania”.

The ring-tailed glider (Tous ayamaruensis) is a relative of the three Australian greater glider species in the genus Petauroides. However, it has a number of fundamental differences, most notably a prehensile tail and unfurred ears, that led researchers to reclassify it in its own genus.

Some of the Indigenous communities of the region regard the glider as sacred and an animal to be avoided and protected, which may have contributed to it remaining unknown to science until now.

“It’s one of the most photogenic animals, most beautiful marsupials you’ll ever see,” says Flannery.

The pygmy long-fingered possum (Dactylonax kambuayai) is a beautifully striped animal with one digit on each hand that is twice as long as its other fingers.

“They’ve got a whole lot of specialisations in their ear region as well, which seem to be related to detection of low-frequency sound,” says Flannery. “So presumably they’re listening for wood-boring beetle larvae, and they then rip open the rotting wood and use that finger to fish out the grub.”

The exact location where the animals live is being kept secret because of the fear that wildlife traders may target the species.

Flannery warns these traders against doing this. “They would be incredibly difficult to keep in captivity. because their diet is so highly specialised. Advanced warning for anyone who’s thinking of keeping one as a pet: it won’t live long,” he says.

The fossil record of the Tous genus is as cryptic as its living presence, says Hucknull. There are 3-million-to-4-million-year-old fossil teeth from sites in Victoria and New South Wales in Australia, then a gap until 280,000 years ago, when fossils at the Mount Etna and Capricorn caves in Queensland suggest that the ancient Tous was a relatively common possum.

“The smallest fossil species is indistinguishable from the Tous now found alive in West Papua,” says Hucknull.

“The pocket-sized, bizarre and cute Dactylonax kambuayai is equally as important as Tous,” he says. “With its massively elongated finger and a small size that would fit in the palm of your hand, it represents a peculiar ecological role.”

David Lindenmayer at the Australian National University, Canberra, says these are “fascinating and important discoveries”.

“I am also hugely concerned about the extent of logging and land clearing happening in New Guinea,” he says. “It also makes me wonder what might have been lost in Australia as a result of all of the land clearing that has taken place here.”

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