In the collections of the Queensland Museum, a tiny marsupial collected in the 1970s had been waiting patiently for someone to notice it. Last year, researchers finally did—and in doing so, uncovered not one but two new species of planigales, among the smallest mammals on Earth. The discoveries remind us that even in well-studied corners of the world, nature still holds secrets.
Planigales are extraordinary creatures. Some weigh just over 2 grams—less than a couple of paper clips—and are roughly half the size of a house mouse. With flattened heads built for squeezing into rock cracks, these miniature predators emerge at night to hunt insects, spiders, and occasionally lizards and young mammals nearly their own size. They inhabit the cracking clay soils of central and northern Australia, areas so remote and these creatures so elusive that conventional traps often fail to catch them.
"Australia is home to unusual mammals not found anywhere else—consider the platypus, Tasmanian devil or red kangaroo," the researchers noted. "But did you know our understanding of this continent's incredible mammalian diversity is still incomplete?"
In the past five years alone, 20 new mammals have joined Australia's species list. The planigale discoveries came after researchers exhaustively examined more than 2,000 specimens held in Australian museum collections. In the Queensland Museum's archives, they found a single specimen that matched genetic samples first identified in 2017 from Kakadu National Park in the Northern Territory. Together with two others—one male and one female preserved in the Museum and Art Gallery of the Northern Territory—these three specimens proved distinct enough to warrant their own species: the Arnhem Plateau planigale, officially named Planigale petrophila, meaning "rock-lover."
Unlike most planigales, which prefer swampy habitats and heavy clay soils, this species was found perched atop a rocky plateau. It is larger than its relatives, with dark grizzled fur and a notably long tail—longer than any other known planigale. Because it is known from only three individuals, researchers are now racing to learn whether it is rare or already under threat.
The second discovery emerged from specimens in the Kimberley region of Western Australia. These animals looked nearly identical to their counterparts in the Northern Territory, Queensland, and South Australia—but genetically, they were anything but. They represent what's called a "cryptic" species, hiding in plain sight until science caught up.
The work was made possible through partnerships with organizations like the Australian Wildlife Conservancy, which surveys mammals in remote stretches of outback. Museum collections spanning more than 200 years proved invaluable—an irreplaceable scientific record of life on Earth that continues to yield discoveries.
As researchers continue their work, the Arnhem Plateau planigale stands as a reminder: even in an era of satellite maps and genome sequencing, the natural world still has room for surprise.