The Giant Echidna (Zaglossus hackettii) which lived in South West Australia until around 55,000 years ago. It is the largest monotreme so far discovered. (Art by Eric Alibert. Image from here)

Australia’s native fauna are undeniably odd and none more so than the curious monotremes (the Monotremata). These egg-laying, milk-producing, furry creatures are mammals, but with organs and body parts that may be more at home in birds or reptiles including a cloaca, an interclavicle bone, and ankle spurs on adult males. These unusual features hint at the ancestry of the monotremes, which are thought to have diverged from the rest of the mammals some 220 million years ago.

The familiar short-beaked echidna (Tachyglossus aculeatus) is Australia’s only remaining species of echidna, although it has been suggested that the western long-beaked echidna, Zaglossus bruijni, may still be found in the Kimberley region of Western Australia. Three more species of long-beaked echidna (Zaglossus spp.) are still found in New Guinea, and several others are known from the fossil record in Australia. But as the First Australians were making their way into the continent it was the largest of these – the Giant Echidna (Zaglossus hacketti) – that trundled its way through the landscape of southwestern Australia.

Known only from a small number of bones found in Mammoth Cave, southwestern Australia, the Giant Echidna was first described by geologist and palaeontologist Ludwig Glauert in 1914. Ten years earlier, Ernest Le Soeuf had been made aware of some unusual bones at this cave and collected several bones of long-extinct mammals. His finds drew the attention of the Hon. Dr John Winthrop Hackett, Chairman of both the Caves Board and the Western Australian Museum. Hackett visited the site in 1905, and recommended further research and excavation of bones from these deposits, offering to fund the costs of fieldwork. However, it was not until 1909 that the Museum managed to secure the services of Glauert, who had emigrated from England to Australia in 1908 with his wife, Winifrede. While on unpaid leave from his employers at the Geological Survey, Glauert and his colleagues collected over 2000 specimens from Mammoth Cave in less than two months, including several previously unknown species. Five years and several seasons of fieldwork later, Glauert and his assistants had collected and identified over 10,000 bone specimens, and described and published three new mammal species, including the Giant Echidna, making the Mammoth Cave fossil fauna one of the most extensively studied in Western Australia.

The media went wild over the extinct Giant Echidna (Zaglossus hackettii) heralding the discovery to be “the palaeontological event of the year”. The excitement was justified: this creature was the largest monotreme ever to have lived, more than twice the size of its closest living relative. At close to a metre in height and weighing in at 30 kilograms or more, this beast was about the same size as an average sheep!

One of the things that make the echidna so unique is its long, tubular snout, which only opens just enough to enable the extremely long, sticky tongue to dart out and capture juicy food – typically earthworms, ants and other small invertebrates. This big beast would have been able to quickly and efficiently decimate an ant colony with a tongue estimated to be almost 50 cm long! It was this massive tongue which gave the animal its name: Zaglossus means ‘ huge tongue’ in Latin. It is difficult to know much about the feeding behaviour of these giants, as cranial bones have not been identified. However, the design of their limbs and body mean that they almost certainly lived off a similar diet of worms and insects like their smaller relatives – only consuming a lot more! They may also have enjoyed larger insects such as moth larvae (Bardi or ‘Witchetty’ grubs) found in the trunks of decaying grasstrees and tree roots.

Modern day echidnas move rather slowly, with stocky legs and spade-like feet. Based on the size and shape of the bones examined by Glauert, it seems likely Zaglottus hackettii moved in quite a similar manner, shuffling through the leaf litter and underbush in search of food. However, there is a small difference to be note; the Giant Echidna of the Pleistocene had slightly different limb proportions to its modern relatives, and as a result its centre of gravity was probably closer to the back legs. Perhaps this allowed the creature to shift its weight back on its hind legs while ripping into decaying tree stumps, termite mounds and ant hills with its powerful forelimbs and strong claws in search of juicy, nutritious bugs?

Like other echidnas, Zaglossus hackettii would have laid eggs into a pouch rather than giving birth to live young like other mammals. The young of all echidnas are called ‘puggles’, and once hatched, are suckled from mammary glands in the similar way as other mammals. The Giant Echidna puggles would have lived safely in mum’s pouch until they begin to grow spines, at which point they were (understandably) evicted, remaining in underground burrows until they are old enough to join their mother to forage for food.

Despite the fearsome spines along this extra large monotreme’s back, its response to danger would have been far more like a hedgehog than a porcupine. The quills were firmly embedded in the animal’s muscle, so unlike a porcupine, they don’t come out of the animal on contact with a predator. Instead, this gentle giant curled into a ball, using its strong limbs to partially burrow into the ground to anchor itself in place. In this way the exposed, quill-ridden hide remained exposed, and the animal waited until the predator loses interest. Once any echidna, megafaunal or modern, has rooted itself to the spot in this way, it would be almost impossible to remove!

It is thought that Zaglossus hackettii became extinct around 55,000 years ago, at around the same time as many of Australia’s other Pleistocene beasts. As in other parts of the world, this timing coincides with the earliest dates we have for the arrival of humans. The causes for the extinction are as yet unknown, but it’s very possible that environmental influences, combined with human activities such as over- hunting and destruction of habitat, contributed to the amazing creatures’ demise. We can only imagine the amazement of the First Australians encountering this unique lumbering, prickly anteater as it became a fading shadow in the twilight of Australia’s Pleistocene fauna.

Written by Carly Monks (@_CarlyMonks)

Edited by Rena Maguire (@justrena)

Further Reading:

Glauert, L. (1914), “The Mammoth Cave (Continued)”, Records of the Western Australian Museum, 1(3), 244-252. [Full article]

Helgen, K. M, et al, (2012), ‘Twentieth century occurrence of the Long-Beaked Echidna Zaglossus bruijnii in the Kimberly region of Australia’, ZooKeys, 255, 103-132. [Full article]

Jenkins, C.F.H. (1983), “Glauert, Ludwig (1879-1963)”, Australian Dictionary of Biography, 9. [Full article]

Long, J., Archer, M., Flannery, T. and S. Hand2002. Prehistoric Mammals of Australia and New Guinea. Sydney: UNSW Press. [Book]