New Guinea: Two marsupials lost for 6,000 years rediscovered

In March 2026, an Australian research team led by zoologist Tim Flannery published two studies with surprising results: On the remote Vogelkop Peninsula in northwestern New Guinea, two marsupial species were found alive that had previously been known only from fossils approximately 6,000 to 7,500 years old.

Such rediscoveries are often referred to as Lazarus species—species long considered extinct or lost that later reappear. Such finds particularly often originate from Australia and New Guinea. The mountain pygmy possum (Burramys parvus) was first described from fossil bones before being discovered alive in 1966. The Bulmer’s fruit bat (Aproteles bulmerae) was likewise initially known only from prehistoric bones. Living animals were not confirmed until 1975. In 2023, Attenborough’s long-beaked echidna (Zaglossus attenboroughi), long documented only by a single museum specimen, was observed again in western New Guinea.

That such rediscoveries occur in New Guinea is hardly surprising. The island is one of the most species-rich regions on Earth and at the same time remains insufficiently explored across large areas. Mountains, dense rainforests, and remote valleys make scientific expeditions difficult—while simultaneously providing refuges for species that have long since vanished elsewhere.

Tous ayamaruensis—A creature between two worlds

Tous ayamaruensis is a small marsupial that defies easy classification. It belongs to the subfamily Hemibelideinae within the ringtailed possums (Pseudocheiridae)—a group that also includes the lemuroid ringtail possum (Hemibelideus lemuroides) and the greater gliders (Petauroides spp.) from eastern Australia.

With Tous, a third genus within this subfamily has been described that combines characteristics of both previously known lineages. Like the lemuroid ringtail possum, the species possesses a strongly prehensile tail, while—similar to the greater gliders—it bears a pronounced skin membrane (patagium) between its fore and hind limbs. Whether this membrane is actually used for gliding has not yet been directly observed; evidence for this comes mainly from anatomical features and reports from local hunters. Should this be confirmed, T. ayamaruensis would be unique within the Hemibelideinae—a creature that can climb, leap, and glide.

The study lists additional features that distinguish the species from its relatives: naked ears, a black ring around the eyes, a dark patch behind the ear, and a narrow, tapering tail without a bushy tip. Body mass is estimated at approximately 300 to 400 grams—considerably less than the one to two kilogram greater gliders of Australia.

The researchers propose the English name Ring-tailed Glider for the species. In the language of the Maybrat communities, however, the animal has long been known and is called Tous wan—from which the scientific genus name is also derived.

Conversations with local elders provide clues about its way of life. According to them, it is a nocturnal, arboreal animal that preferably lives in hollows of large rainforest trees, particularly in merbau (Intsia bijuga) and ironwood (Kayu Besi). Pairs are said to raise only a single offspring per year.

According to reports from the region, the animal leaves scratch marks on tree bark and partly feeds on exuding tree sap. Its diet presumably also includes leaves, fruits, and invertebrates.

How the discovery came about

The scientific story begins in 1999. That year, the Australian zoologist Kenneth Aplin described subfossil bone fragments from Kria Cave on the Ayamaru Plateau: a broken mandible and several teeth from early Holocene layers, approximately 7,500 to 6,000 years old. Aplin initially classified the animal as “Petauroides” ayamaruensis and assumed that the species had long been extinct.

A first indication of its possible survival emerged in 2015. An employee of a palm oil company photographed a small nocturnal marsupial near Sorong, which he initially mistook for a slow loris or a cuscus. The images eventually reached zoologist Kristofer Helgen, who recognized that it could be a living specimen of ayamaruensis.

In the following years, further evidence accumulated. Fossil finds from sites near Vanimo in Papua New Guinea expanded the known material of the species. In 2023, another living animal was photographed on Misool Island. In September 2024, hunters there documented a killed specimen—the photographs taken definitively confirmed that the species still exists today.

Based on additional fossil finds from Papua New Guinea, the researchers suspect that the species may have also survived in other rainforest regions—such as the Mamberamo Basin or the Torricelli Mountains. However, confirmed records of living animals from these areas do not yet exist.

Dactylonax kambuayai—A miniature finger acrobat

The second rediscovered species, Dactylonax kambuayai, belongs to the subfamily Dactylopsilinae within the Leadbeater’s possum and lesser gliders (Petauridae). Today, this family comprises three subfamilies with a total of four genera and around 16 species.

The subfamily Dactylopsilinae includes trioks and striped possums. These animals are characterized by dark stripes on their backs and, in the case of the genus Dactylonax, a greatly elongated finger.

In the new study, the systematics of these animals was revised: The researchers recognize Dactylonax once again as a distinct genus. In addition to the rediscovered pygmy long-fingered possum, it comprises two further species: Dactylonax palpator and Dactylonax ernstmayri.

Characteristic of these animals is a greatly elongated fourth finger, which they use to probe rotting wood for insect larvae. A similar strategy is known from the aye-aye (Daubentonia madagascariensis) of Madagascar—a classic example of convergent evolution.

D. kambuayai is the smallest member of this group. The only precisely measured female weighed just approximately 216 grams. Despite its small body size, the elongated finger is just as long as in considerably larger relatives of the genus, and relatively speaking even longer.

Also notable are the ears, which are large relative to the body at approximately three centimeters in length. Unlike the black-and-white striped possums, D. kambuayai displays a markedly less contrasting pattern. A pale band running from the muzzle to below the eye is considered another distinguishing feature.

The winding discovery story

This species, too, was initially known only from fossils. In 1999 Kenneth Aplin described mandible fragments from Kria Cave at Lake Ayamaru as Dactylopsila kambuayai (Arfak striped possum)—unusual teeth from Holocene layers, approximately 7,500 to 6,000 years old, that could not be assigned to any known living species. The fossils of T. ayamaruensis also originate from the same cave.

Years later, Aplin searched the teaching collection at the University of Papua New Guinea in Port Moresby. There he discovered two overlooked specimens in a jar of alcohol, mislabeled as long-fingered possums (D. palpator). They turned out to be an adult female with a young in its pouch, collected by zoologist Patricia Woolley as early as 1992 in the village of Nenei in the Arfak Mountains. Because she believed the animal to be a known species, its true identity remained unrecognized for decades. Aplin recognized the significance of these specimens during his lifetime; however, the scientific description was not completed until after his death in 2019, by his co-authors.

Further evidence followed from 2023 onward. During a mammal-watching tour led by Carlos Bocos and Jon Hall near the village of Klalik, located 65 kilometers northwest of Kria Cave, a villager brought a living animal to the group. It was photographed and subsequently released. The images first appeared on the platform Mammalwatching and later helped in identifying the species. Additionally, several photographic records from the region exist on the citizen science platform iNaturalist.

Vogelkop: A refuge of Earth’s history

Why two marsupials long thought to be extinct reappear on the Vogelkop Peninsula of all places can be explained by a look at Earth’s history. During the last ice age, sea levels were significantly lower than today. Australia and New Guinea were connected by land bridges, and what is now the Arafura Sea was dry land. Together, both regions formed the continent of Sahul, where many animal groups evolved together. This is why numerous fossil species from Australia have their closest living relatives in New Guinea today—and vice versa.

Tous is a good example. Two additional representatives of the genus are known from the Australian fossil record: Tous stirtoni from the early Pliocene of Victoria (approximately 4.5 million years ago) and a hitherto undescribed species from the middle Pleistocene of Queensland. The genus was thus once distributed across the Australian continent. Today, only T. ayamaruensis appears to have survived—in the rainforests of the Vogelkop. The same applies to Dactylonax: Pleistocene fossils demonstrate that this lineage once also occurred in Australia, while its present-day representatives live only in New Guinea.

The largely intact rainforests of the Vogelkop Peninsula may have served as a refugium in which these ancient marsupial lineages persisted while their relatives disappeared elsewhere. Misool Island likely also played a role: during the ice age, it was connected to the mainland and may have served as a retreat—which would explain why Tous has also been recorded there.

A refuge under pressure

The rediscovery of the two marsupials is spectacular news, but their survival is by no means assured. Both species appear to occur only in a small area of the Vogelkop Peninsula and may thus be among the most geographically restricted mammals in New Guinea.

The ringtail possum T. ayamaruensis appears to be particularly dependent on old, large trees—precisely those forest giants that are intensively harvested as valuable tropical timber. These trees apparently serve the species as roosting sites, while its food likely comes from other, as yet unidentified tree species. Its presumably low reproductive rate also makes it vulnerable to excessive hunting. Local informants additionally reported to the researchers that the species in the Sorong area, where an animal was still photographed in 2015, has possibly already disappeared due to deforestation.

The forests of the Vogelkop Peninsula are also increasingly under pressure. Logging, oil palm plantations, cattle ranching, and local population growth are transforming the landscape in many places. In the Arfak Mountains, the Arfak Mountains Nature Reserve protects approximately 63,000 hectares of the region’s montane and lowland forests. However, large forested areas outside the protected zones remain unsecured.

For the pygmy long-fingered possum D. kambuayai, the situation may be somewhat more complex. Finds from the Klalik region suggest that the species occurs across larger parts of the northern Vogelkop Peninsula. Since it has also been recorded in slightly disturbed lowland forests, suitable habitats may still exist over larger areas. At the same time, the lack of additional records could also be due to the fact that nocturnal mammals in the lowland regions of West Papua have rarely been systematically surveyed to date.

For this reason, the study authors deliberately refrain from publishing precise localities of living animals. They fear that rare species could quickly attract the attention of the wildlife trade through social media—a problem that has been difficult to control in Indonesia and has already severely decimated numerous forest species.

At the same time, the researchers emphasize that little is still known about the actual distribution of both species. This makes targeted field studies all the more important to identify areas where stable populations exist. Only in this way can the forests on which these animals depend be protected in the long term.

How lost species are found again

The rediscovery of these two marsupials also shows how the search for “lost” species is changing. The key was not a classic expedition in the style of early naturalists, but the interplay of different knowledge sources. Without the Maybrat elders, who had known the Tous wan for generations and could describe its way of life, the connection between fossil finds and living animals would hardly have been established so quickly. And without the chance snapshot by a plantation worker in 2015, perhaps no one would have begun searching for the animal in a targeted manner.

The researchers see this as a model for future discoveries. Large parts of New Guinea remain biologically insufficiently explored. Numerous animal species known from archaeological caves and subfossil deposits are today considered to have vanished. Some may still exist in remote rainforests—such as in the Raja Ampat Archipelago, the Foja Mountains, or the Torricelli Mountains. The combination of cave archaeology, local knowledge, and targeted field research opens up possibilities that no technology alone can offer.

The story of Tous ayamaruensis and Dactylonax kambuayai shows how surprising such discoveries can be. Two marsupials, known only from fossils for approximately 6,000 years, suddenly reappear in living form—discovered through museum finds, chance photographs, and the knowledge of people who have lived in these forests for generations.

At the same time, their rediscovery reminds us how little we still know about some regions of the Earth. The forests in which these animals have persisted are among the last great refuges of biodiversity—and their protection will determine whether such species survive in the future.

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Sources

• Flannery, T. F., Aplin, K. P., Bocos, C., et al. (2026): Found Alive After 6,000 Years: Modern Records of an ‘Extinct’ Papuan Marsupial, Dactylonax kambuayai (Marsupialia: Petauridae), with a Revision of the Systematics and Zoogeography of the Genus Dactylonax. Records of the Australian Museum 78(1),17–34.
  https://doi.org/10.3853/j.2201-4349.78.2026.3003
• Flannery, T. F., Koungoulos, . G., Meijaard, E., et al. (2026): A new Genus of Hemibelideine Possum (Marsupialia: Pseudocheiridae) from New Guinea and Australia, Including a Lazarus Taxon from the Vogelkop Peninsula. Records of the Australian Museum 78(1), 35–52.
  https://doi.org/10.3853/j.2201-4349.78.2026.3004