Those who venture into Foul Air Cave, below Buchan township in eastern Victoria, quickly realise how it got its ominous name. In its deepest chambers, bacteria consume oxygen and excrete organic gases to produce a toxic stench.
The cave is also a natural pitfall trap. Its water-worn entrance offers no escape to any creature unlucky enough to tumble in. The smell of death clings to your nostrils as you navigate vertiginous drops and calf-deep, sucking mud.
Tens to hundreds of thousands of years ago during the Pleistocene Epoch, Foul Air Cave accumulated remains of diverse, often-giant mammals known collectively as Australia's megafauna .
One of these mammals was the giant echidna Megalibgwilia owenii, as we report in a new paper published today in Alcheringa: An Australasian Journal of Palaeontology. We recognised this extinct monotreme, twice the size of Australian echidnas today, from a newly identified fossil collected almost 120 years ago.
And the specimen is enough to verify for the first time that this species once roamed Ice Age Victoria, spanning a 1,000 kilometre gap in its previously known distribution.
Scores of ancient bones
The first scientific expeditions to Foul Air Cave were made in 1906-7 by Frank Palmer Spry who worked for what's now called Museums Victoria, local caves curator Francis Moon, and geologist Thomas Sergeant Hall.
They were among the first to enter the cave. They encountered scores of fossil bones loosely buried in damp earth, including powerful, clawed mega-marsupial palorchestids and predatory marsupial "lions".
They deposited their finds in the state collection, now housed at Melbourne Museum .
Over a century later, the fossils of Foul Air Cave have granted us a further insight into deep time.
A robust creature
Previously described fossils of Megalibgwilia owenii derive from a handful of sites in Western Australia, South Australia, Tasmania and New South Wales. They're sparse, too: one well-preserved skeleton, four skulls of varying completeness, and a range of isolated bones.
Together, they illustrate a robust mammal a metre long and weighing in at 15 kilograms - roughly as big as a four-year-old child.
The meaning of its name is straightforward. Mega-libgwil-ia joins the ancient Greek prefix "mega-", meaning large or mighty, with " libgwil ", the name for the echidna in the language of the Wemba Wemba people of northern Victoria and south-eastern NSW.
We can combine this with the species epithet owenii (acknowledging prolific 19th century anatomist Sir Richard Owen ) to coin a common name: "Owen's giant echidna".
Using its fossil remains as a guide, Owen's giant echidna most resembled the long-beaked echidna (Zaglossus), which today occupies the wet tropical cloud forests of New Guinea. Its broad limbs and shoulders bore prominent bony scars indicating it was more heavily muscled than other monotremes. It also had a wide, long and straight untoothed beak, with bony ridges across its palate.
This suite of differences implies Megalibgwilia was adapted to a different lifestyle than its modern relatives. One can imagine it tearing to pieces fallen logs or digging hard soils to seek out moth and beetle larvae, rather than feeding on termites or earthworms.
A fossil awaits its finder
Our new fossil came to light during the systematic documentation and maintenance of thousands of fossil bones, teeth, and skeletons preserved by Museums Victoria.
But even this obscure seven centimetre fragment of skull was sufficient to identify the unique proportions of M. owenii - especially when we examined material in museum collections across Australia.
As well as identifying the fossil, we also researched its connection to Foul Air Cave by drawing on collection notes, hand-drawn maps, diaries and public newspaper archives .
These historical ephemera established Spry as the fossil's collector. And they inspired a return to the cave in his footsteps.
Ready for re-examination
Spry and Moon wore their everyday outfits of breeches, jacket and waistcoat for their fossicking. They lit their path with candles or kerosene lamps, and entrusted their life to stiff, heavy nautical rope. The trained geologist Hall never ventured into the cave himself. Under those conditions, who would judge him?
By comparison, modern caving is a technical affair. Brilliant headlamps illuminate entire caverns. Heavy-duty nylon oversuits protect from skin-shredding rocky surfaces. And the climbing ropes and devices are strong enough to suspend a small car.
The collaboration between Spry, Moon and Hall combined an informed perspective, fluent local knowledge, and technical know-how to succeed. Despite obvious advances in technology and disciplinary knowledge, our success is rooted in the same foundation as theirs - curiosity and community spirit.
During my own investigations at Buchan, families spanning generations have shared local history and acted as subterranean guides. Parks Victoria rangers have facilitated and overseen work on public reserves . Recreational cavers from the Victorian Speleological Association have been a wellspring of enthusiastic support.
The long residence of this specimen in Victoria's state collection epitomises how, thanks to past work, palaeontological discoveries arise from "collection-based" fieldwork as often as investigations outdoors.
And if one illuminating specimen can lie unnoticed across a century, why not others?
Sparse fossil bones of large, slender echidnas, seemingly distinct from Megalibgwilia owenii, have been noted from Victoria and South Australia. These warrant re-examination to test if Owen's giant echidna adapted to different conditions over space or time, or if another unknown species co-occupied the landscape.
The latter option is intriguing in light of the proposition that Zaglossus may even have occupied northern Australia until as late as the 20th century.
If true, then surely one of its ancestors awaits recognition - either among the landscape or preserved carefully among the nation's public scientific assets.
Tim Ziegler is affiliated with the Victorian Speleological Association.
