Late at night a few years ago a villager approached a group of mammal-watchers in the remote forests of West Papua, holding a peculiar possum.
The mysterious marsupial had a giant finger on each hand.
Now its identity has been revealed thanks to a collaboration between scientists and West Papuan elders.
The animal was a pygmy long-fingered possum (Dactylonax kambuayai) previously only known in modern science from 6,000-year-old fossils.
It is one of two "Lazarus taxa", alongside the ring-tailed glider (Tous ayamaruensis), from the remote rainforests of the Vogelkopf (Bird's Head) Peninsula described in a pair of new studies.
Lazarus taxa — a designation coined from the biblical figure said to have been raised from the dead — are species that show up alive when they are only previously known from material like fossilised remains.
The studies of the possum and glider, published in Records of the Australian Museum journal, adds to growing knowledge on the 100 or so marsupials that live in New Guinea and its surrounding islands.
This in turn adds to our understanding of the evolution of marsupials in the Australasian region.
But with little known about the elusive animals there are concerns for their conservation status due to threats from industries like logging.
Study lead author and mammalogist Tim Flannery, a distinguished visiting fellow to the Australian Museum, said knowing whether the animals lived in protected areas was critical.
"There's some areas that have been heavily logged in the Vogelkopf that local people say, 'Well, it [ring-tailed gliders] used to occur here, but it no longer does,'" Professor Flannery said.
"We just have to determine where the thing lives, which areas are protected under the national park system in order to get that conservation kind of perspective."
Wildlife ecologist Euan Ritchie, a professor at Deakin University not involved in the study, said it was a "joyous" find.
"In a world awash with bad news, and no more so than for the environment, it is always joyous when species once thought extinct turn out not to be, and new ones are also described."
What is a pygmy long-fingered possum?
The pygmy long-fingered possum can grow to about 17.6 centimetres, not including an 18cm tail.
It has a head that looks similar to another small marsupial, the sugar glider.
"[The possum is] boldly striped in black and white," Professor Flannery said.
"But its most distinctive feature is that the fourth digit on its hand is about twice as long as any other digit and it's used for extracting wood-boring beetle larvae out of wood."
Specimens of the possums were collected in 1992 in the small village of Nenei in the Arfak Mountains but improperly identified at the time.
The late zoologist Kenneth Aplin, listed as a co-author of the new studies, thought the old specimen could be a pygmy long-fingered possum, which he had previously described from fossil records.
But he died in 2019 before the work with Professor Flannery and Indonesian and Papuan scientists could be completed.
[map possum]Since then, the possum has been seen on mammal-spotting tours near Klalik village in the north west of the Vogelkopf Peninsula.
The scientists linked the more recently photographed possums with the adult skull and fossils to reveal the marsupial's identity.
What is a ring-tailed glider?
The ring-tailed glider with its bulging eyes looks similar to a primate from Madagascar, the sportive lemur.
Elders from the Tambrauw and Maybrat language group area of West Papua said the glider was known as "Tous wan" when shown photos.
"In some areas of the Vogelkopf [the ringtail] is the most sacred animal in their cosmology," Professor Flannery said.
The locals also consider the area the animal lives in, which is a magnificent old-growth forest, to be something like the centre of the universe, he added.
"It's the place where all of the living things came from."
Elders Barnabas Baru and Carlos Yesnat said the creature was a skilful leaper with a tail that could grab branches and vines.
The nocturnal species eats leaves and uses its claws to extract tree sap that is left to congeal before being eaten.
[map ring-tail]Fossilised jaw fragments dated about 6,000 years old were originally described in 1999 from Kria Cave in the Vogelkopf Peninsula.
These fossils, along with more found at other sites, shared similarities with Australian gliders.
In recent years, photos of the glider have been taken at Vogelkopf Peninsula and Misool Island.
The study's authors suspected the species from the fossil record could still be alive since the region was under-surveyed for marsupials.
They concluded similar characteristics shared by the photographed gliders and the fossils, along with traditional knowledge of the species, was enough to identify it as a Lazarus taxa.
Evolutionary biologist Steven Cooper, a professor from the SA Museum and University of Adelaide who was not involved in the study, said the two newly described species were extraordinary discoveries from a hot bed of mammal diversity.
He said the animals most likely evolved in New Guinea when the central mountain range started uplifting after the collision of the Australian and Pacific plates, millions of years ago.
"They also highlight the value of incorporating Indigenous knowledge with scientific approaches of traditional taxonomy to fully comprehend the incredible diversity of this region of the world."
Exact glider locations kept secret
The Vogelkopf Peninsula is full of remote and hard-to-navigate terrain but researchers are keeping the known locations of ring-tailed gliders under wraps.
There is a risk of people trying to take the animals from the wild, threatening the survival of the species.
"I fear that if there was anyone trying to trade them ... the animals would live a very short time," Professor Flannery said.
Professor Ritchie said it was a tragic reality that, even as some species were being described, others unknown to science may be heading towards extinction.
"Funding for biodiversity surveys and taxonomy has declined and is grossly inadequate in Australia, and much of the world," he said.
"It is sobering to think of what natural wonders and mysteries we might never understand and appreciate because of insufficient funding, yet we continue to spend billions annually on wars."
