Two Marsupials Rediscovered in Western New Guinea After 6,000 Years

In the mountains of western New Guinea, a research team has made a discovery nobody expected: two dwarf marsupials believed to have vanished thousands of years ago appear to have survived there, unnoticed. The finding compels biologists to rethink their understanding of wildlife on this vast Pacific island.

A “comeback” after 6,000 years

Until recently, scientists knew the long-fingered pygmy possum (Dactylonax kambuayai) and the ringtail glider (Tous ayamaruensis) only from teeth and bones discovered in caves in western New Guinea during the 1990s. The youngest fossils were about 6,000 years old. Both species were therefore regarded by specialists as effectively extinct.

An international team led by Australian researcher Tim Flannery and zoologist Kristofer Helgen has now demonstrated otherwise. In the difficult-to-reach forests of the Bird’s Head Peninsula in Indonesia’s Papua province, they documented both animals alive. This breakthrough followed years of demanding fieldwork and painstaking analysis of photographs, trap captures and tissue samples.

Specialists refer to animals in cases like this as “Lazarus species”: creatures that reappear unexpectedly after seeming to have become extinct.

The first clue emerged in 2019, when a local observer sent in a photograph of an unfamiliar small marsupial. At the time, it was unclear whether it truly belonged to one of the species known from fossils. Confirmation has only now come through comparisons of skull and tooth morphology, fur patterning and genetic material.

There is a sad element to the story: palaeontologist Ken Aplin, who first described the species from the fossils, died in 2019 before he could witness proof that they still existed. Even so, his work provided the basis for today’s reassessment.

Two tiny marsupials with remarkable specialised abilities

The “long-fingered” marsupial

The long-fingered pygmy possum weighs only around 200 grams, roughly the weight of a medium-sized apple. It belongs to the striped glider family and is its smallest known member. Its name is well earned: on each hand, its fourth finger is noticeably longer than the others.

The animal uses this specialised digit as a highly sensitive tool. It probes cracks in tree bark, detects hidden insect larvae and then pries them out. This resembles the feeding method of Madagascar’s aye-aye, although the adaptation developed independently through evolution.

• Weight: around 200 grams
• Habitat: the canopy and trunks of old rainforest trees
• Diet: mainly insects and other invertebrates beneath bark
• Distinctive feature: a greatly elongated fourth finger on each hand

This highly specialised technique gives the pygmy possum access to a food source that few other tree-dwelling animals exploit. As a result, it faces less competition and occupies its own ecological niche.

The ringtail glider

The ringtail glider is slightly larger, weighing about 300 grams. Like other gliders, it has a gliding membrane: an expandable flap of skin stretching between its forelimbs and hindlimbs, allowing it to sail from one tree to another. Leaping, gliding and landing in rapid sequence enables it to travel long distances through the canopy without touching the ground.

Its prehensile tail is a defining feature. This flexible tail, marked with ring-like patterns, grips branches and lianas, steadies its leaps and assists with climbing. Unlike many other small mammals, the ringtail glider apparently has a social life strongly centred on pair bonds.

According to the Australian Museum, these animals generally live in monogamous pairs. A female produces only one young each year, an exceptionally low reproductive rate for a small mammal. That makes the species particularly vulnerable to disturbance and habitat loss.

The ringtail glider is the first new marsupial “genus name” described in New Guinea since 1937 – a genuine landmark for taxonomy.

For the Indigenous Maybrat community, the animal is more than a research subject. It is regarded as sacred and features in stories, teaching traditions and rituals. To villagers, it had never been “missing” - science had simply lost sight of it.

Secret coordinates and a race against chainsaws

The expedition could only take place because researchers worked closely with the Indigenous Tambrauw and Maybrat groups. Local people’s knowledge of the landscape and its animals guided the team to remote forest areas that few outsiders can enter.

A Maybrat woman, Rika Korain, contributed to the study as a co-author and helped ensure the animals were identified correctly. Her information about their behaviour, occurrence and cultural importance complemented the scientific measurements and samples.

Yet confirmation of the species also brought a new concern: fear of wildlife traders. Rare marsupials with an appealing appearance can command high prices on the black market. The research team has therefore withheld the precise discovery locations. Only the broader area, the old-growth forests of the Bird’s Head Peninsula, is known.

These forests are increasingly under pressure. Road construction, logging and agricultural development are pushing further into the landscape. Many areas are being converted into palm oil plantations or other monocultures. For specialised canopy dwellers such as these two marsupials, that means: no old trees, no future.

What the discovery reveals about gaps in knowledge

The rediscovery of these two species starkly demonstrates how incomplete knowledge of wildlife in remote regions remains. New Guinea is among the world’s most species-rich islands, yet large parts of its mountainous interior have received little biological study.

Experts consider it possible that other supposedly vanished species may still survive in inaccessible valleys and mountain forests. Small nocturnal animals, especially those that live in the canopy, are particularly easy for people to overlook.

• Many rainforest areas have never been systematically mapped biologically.
• Observations from local communities are too rarely incorporated into studies.
• Species with small distributions can easily go unnoticed.
• Fossils reveal little about whether a species has truly disappeared.

Lazarus species such as these two marsupials show how risky broad statements about extinction can be. Fossils demonstrate that a species occurred in the past, but do not necessarily prove the end of its lineage. Without current field research, many questions remain unanswered.

Why protecting old forests benefits everyone

Old rainforests such as those on the Bird’s Head Peninsula perform several functions at once: they provide habitat for specialised species, store carbon and regulate water. Protecting them safeguards not only individual animals, but entire ecosystems.

Species that reproduce slowly and have small bodies often play underestimated roles in forests. They disperse seeds, consume particular insects or serve as prey for larger predators. If one of these functions disappears, the whole system can be thrown out of balance.

For local people, these forests are also closely tied to cultural identity, traditional food and spiritual beliefs. When an animal such as the ringtail glider appears in stories and teaching narratives, its loss is more than a biological one - it leaves gaps in the social fabric.

What readers can take from this

The story of these two marsupials has several dimensions. It illustrates how persistently species can endure, even after they have long vanished from textbooks. It underlines that conservation rarely succeeds without local communities. And it makes clear that protective action must begin early, rather than only when the last population is close to collapse.

People may not be able to intervene directly in New Guinea through their daily choices, but they can support organisations securing rainforest land or choose products from supply chains linked to less deforestation. Every hectare of old forest left standing also protects potentially unknown species that have not yet been described.

These two reappearing marsupials therefore offer a powerful argument: while intact habitats still exist, there remains a chance that “lost” species are surviving somewhere in the shade of old trees.