¶ According to a statement from the Australian Museum, the two species were previously known from Pleistocene fossils in Australia and fossils dating from the Pleistocene to the early Holocene in New Guinea. According to Live Science, the findings come from two peer-reviewed studies.
From fossils to new photographs
The pygmy long-fingered possum had previously been known from fossils around 6,000 years old, as ABC News reported; a specimen collected in 1992 was misidentified at the time. In 2022, Carlos Bocos photographed the animal on a mammalwatching.com trip. Researchers linked the photographs to a skull and fossils. Flannery explained that the long fourth finger is used to extract beetle larvae from wood. For the ring-tailed glider, jaw fragments around 6,000 years old from Kria Cave, described in 1999, are known, according to ABC News. In 2015, Ichlas AlZaqie of the Orangutan Foundation Indonesia photographed an animal that Arman Muharmansyah had caught; according to Discover Magazine, researchers compared photographs with fossils and spoke with Indigenous landowners, confirming the species' survival and allowing the introduction of the genus Tous.
According to ABC News, such rediscovered animals are called “Lazarus taxa,” named after the biblical figure who, according to tradition, rose from the dead: species that turn up alive after previously being known only from material such as fossils. According to ABC News, the pygmy long-fingered possum can grow to about 17.6 centimetres long, with an additional 18-centimetre tail. The ring-tailed glider is related to the Australian greater glider but is smaller, has hairless ears and weighs around 300 grams, about half as much as the smallest greater gliders. It forms lifelong pair bonds and raises only one offspring each year. The species represents the first newly described genus of New Guinean marsupials since 1937.
Co-author Rika Korain, a Maybrat woman, said the identification would not have been possible without collaboration with the traditional owners, according to the Australian Museum. Elders of the Tambrauw and Maybrat language groups recognised the glider as “Tous wan”; elders Barnabas Baru and Carlos Yesnat described it as a skilled jumper whose tail can grasp branches and vines. Flannery acknowledged, according to Mongabay, that his team had initially not understood how sensitive and culturally significant the animal was. Biologist James Kempton objected that terms such as “Lazarus species” reflected only the perspective of Western scientists; the discoveries were actually reports of knowledge that Indigenous communities had long possessed.
H2 Fossil record and species conservation
¶ A systematic study of Late Quaternary vertebrate remains from two cave sites in the Ayamaru Lakes region of the central Vogelkop Peninsula documented 41 mammal species and three bird species. The sources differ in their descriptions of the extent of the fossil record: Live Science mentioned only Australian fossils, while the Australian Museum and Discover Magazine also mention fossils from New Guinea. The three Australian Petauroides species to which the ring-tailed glider is related glide through treetops using fur-covered gliding membranes, according to Live Science.
Both species are considered threatened: like greater gliders, the ring-tailed glider nests in hollows in tall forest trees, making it vulnerable to logging, according to Live Science; the pygmy long-fingered possum is also threatened by logging. According to Tambrauw elders, the ring-tailed glider has already disappeared from parts of its former range near the city of Sorong since forests there were cleared. A local guide from the village of Klalik reported that plantation companies had set their sights on the lowland forests of the Klasow Valley for oil palms, near the site where the pygmy long-fingered possum was found. Much remains unknown about the precise ranges and ecological needs of both species, according to Live Science. Researchers are keeping the exact locations secret to prevent wildlife traders from targeting the animals for removal from the wild. Flannery announced plans to support traditional land rights alongside conservation measures such as national parks; in his view, conservation has no long-term future without the involvement of traditional forest owners.