That speculation comes from the discovery that at least one long-beaked echidna, anthought to exist only in New Guinea, was found in Australia in 1901 and that native Aborigine populations reported seeing the animal more recently. The 1901 specimen, described in the Dec. 28 issue of the journal Zookeys, had been shot and stuffed and was lying in a drawer, long forgotten, in the Natural History Museum in London.
"What's amazing about this study is it all hinges on a single specimen, and it's a very well-documented specimen that was collected in 1901 in Australia," said study co-author Kristofer Helgen, a zoologist at the Smithsonian Institution in Washington, D.C. "It's taken until 2013 for myself and the team to really unbury the specimen from the cabinets of the Natural History Museum of London."
Monotremes, which include bizarre little mammals like the , lay eggs like reptiles but feed their babies milk. They may have diverged from all other mammals as far back as the Triassic Period, which lasted from about 248 million to 206 million years ago. 
While short-beaked echidnas and duckbill platypuses still live in Australia, the long-beaked echidna, the largest monotreme in the world, was thought to live only in rainforests of New Guinea. The secretive creature, which can weigh up to 20 pounds (9 kilograms), is listed as critically endangered by the International Union for Conservation of Nature.
Forgotten in a drawer
Scientists knew the spiny,once inhabited Australia but thought it died out after the last ice age, between 30,000 and 40,000 years ago, when New Guinea and Australia were one continent, Helgen said.
Helgen said he was visiting the Natural History Museum in London to look at its collections when he happened upon a skinned long-beaked echidna that was neatly tagged with the species name and where it was discovered.
It turns out that in 1901, an Australian naturalist named John Tunney shot the echidna on Mount Anderson, a mountain in a vast, arid and sparsely populated region of northwest Australia, while on an expedition for a British collector. Tunney, who was trained in taxidermy, stuffed and delivered the specimen, which was later bequeathed to the Natural History Museum. There it lay forgotten for a century.
Once they realized the echidna had been spotted in recent history, the team went back to aboriginal communities in the West Kimberley region. Some of the women remembered watching their parents hunt long-beaked echidnas.
"They remembered that there used to be an echidna in the area that was much larger, and they pointed to pictures of the modern long-beaked echidna from New Guinea," Helgen told LiveScience.
Still out there?
The new findings raise the possibility that the long-beaked echidna is still out there in Australia, and scientists should lead an expedition to find it, Helgen said. But the elusive, criticallyare difficult to spot even in New Guinea. They venture out at night, avoid humans and curl up into a spiky, unidentifiable ball at the first sign of danger, he said.
The discovery not only points to the importance of maintaining museum collections, it radically changes the picture of long-beaked echidnas, said Christopher Norris, a museums specialist at the Yale Peabody Museum of Natural History, who was not involved in the study. The New Guinea rain forest where long-beaked echidnas are normally seen is dramatically different from the rocky, arid scrubland of the Kimberley, Norris told LiveScience.
"It overturns our ideas about how this particular animal lives," he said.
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