Australia's Vanished Beasts

Marsupial Lion
Thylacoleo carnifex

"Few extinct mammals have aroused so much curiosity, so much conjecture as to their way of life and their relationship to other forms as the enigmatic marsupial lion," the paleontologist Rod Wells has written. What Wells and other experts know about this creature they have gleaned from fossil bones, including the complete skeleton discovered in 2002 and featured in "Bone Diggers." Despite its name, T. carnifex was no lion. It raised its young in a pouch, like all marsupials, and its anatomy suggests it was built for dropping onto prey animals from trees rather than chasing them down. Once it grabbed hold of a victim, with help from its large, clawed thumb, the marsupial lion may have dragged it into a tree (as shown here) to devour it.

Diprotodontid
Diprotodon optatum

This was the first fossil mammal from Australia given a name (in 1838). Meaning "two forward teeth," Diprotodon featured two incisors that jutted straight out from its upper jaw, giving it a buck-toothed look. It may have sported a trunk as well, though experts will never be sure unless they turn up a mummified carcass (like the dessicated remains of giant ground sloths found in caves in the Americas) or perhaps unequivocal rock drawings by ancient Aborigines, who are known to have lived alongside diprotodontids for at least 10,000 years. From its teeth, experts have determined that the plant-eating Diprotodon was a browser. Here, a mother watches helplessly as its infant bogs down in mud on the edge of a drying lake.

Palorchestid
Palorchestes (genus)

This animal has been deemed "among the most unusual mammals ever to have lived." It bore massive forearms with impressive claws, which it may have used to rip bark from trees, as seen here. The palorchestids may have been the Australian equivalent of the giant ground sloths of the Western Hemisphere. Their remains have turned up only in eastern coastal Australia, which today has extensive wet and dry forests; indeed, this animal may have been confined to woodlands. The shape and positioning of the nasal bones in its skull suggest it had a trunk, though, again, experts can't be certain. The palorchestids have no modern analogues—when they went extinct, their line ended.

Monodactyl Kangaroo
Sthenurus (genus)

In 1873, working only from fragments of skulls and jaws, the British comparative anatomist Sir Richard Owen named this genus of kangaroo Sthenurus, meaning "strong-tailed beast." Owen was prescient, for a century later when full skeletons were uncovered, this creature was revealed to have a tail stronger and shorter relative to body size than that of all living kangaroos. Its anatomy and teeth suggest it was a large, leaf-eating ‘roo that walked almost exclusively on its monodactyl ("one-toed") hind feet. The only survivor of its lineage may be the banded hare-wallaby, which survives on only two small islands off the coast of Western Australia.

Giant Rat Kangaroo
Propleopus oscillans

One of the rarest and least understood of the extinct Pleistocene marsupials is the giant rat kangaroo, which is known from fewer than 20 individual specimens, most of them represented by jaw bones. Its jaw and teeth are similar to those of the living musky rat kangaroo, but, befitting its megafaunal status, it was much larger, weighing up to 150 pounds compared to the roughly 18 pounds of its surviving cousin. Based on its dentition, experts have suggested that it may have been both a meat- and plant-eater. Like the baboon, for instance, it may have been an opportunistic feeder that dined on meat, eggs, insects, and vegetation. Here, a giant rat kangaroo devours emu eggs.

Giant Goanna
Megalania prisca

You would not want to have run into a hungry giant goanna. For one thing, its kind was huge: experts have estimated that the largest M. prisca for which there is some fossil evidence was 23 feet long and weighed about 1,350 pounds. That's about eight times the mass of the living Komodo dragon, which the giant goanna may have resembled in basic ecology and behavior. Like the Komodo, it may have lurked in undergrowth before ambushing prey—such as the diprotodontid downed at a waterhole in this illustration—then ripped apart its victim with its large, serrated teeth. (Its genus name means "great ripper.")

The Quinkan
Quinkana fortirostrum

In 1970, deep inside Australia's Tea Tree Cave, a caver discovered a skull lying upside down on the cavern floor. It turned out to be from a large, previously unknown crocodilian. The reptile resembled an extinct type of croc called a ziphodont, whose snouts were both broad and deep. (The snouts of most of today's crocs are broader than they are deep.) The caver's find was subsequently named after the "quinkans," mythical humanoids of the Dreamtime, the creation time in Aboriginal mythology. Growing to perhaps 10 feet in length, the land-based quinkan was one of the largest carnivores of the Australian Pleistocene and probably was capable, like the giant goanna, of taking down the largest marsupials, including diprotodontids.

Giant Australian Python
Wonambi naracoortensis

The longest surviving snake in Australia today is the carpet python, which grows to not much longer than 10 feet in length. The extinct giant Australian python, by contrast, was thought to reach over 16 feet long. It is similar to other extinct giant boids from Patagonia, Madagascar, and northern Africa, suggesting they all shared a common ancestor when the southern continents were attached to one another in the ancient supercontinent Gondwana. Much remains unknown about W. naracoortensis, however. Did it lay eggs or give birth to live young? How widely was it distributed? How long did it live on Earth? Future fossil discoveries may tell.

Mihirung
Genyornis newtoni

This giant flightless bird compared in size to the biggest of New Zealand's extinct moas and Madagascar's extinct elephant birds—the largest birds that ever lived. But anatomically it is different from all other birds, including Australia's living emus. Altogether, at least six genera and eight species of mihirungs—which are commonly known as thunderbirds—lived in Australia in the past 15 million years; all are extinct. What role humans might have played in their extinction remains unknown, although people and mihirungs did overlap. Indeed, one Aboriginal tribe had a name for "giant emus"—mihirung paringmal. Here, a mihirung collects pebbles from a Genyornis carcass; the swallowed pebbles help break down food.

Giant Coucal
Centropus (genus)

"Giant" is relative here—this bird was simply bigger than all existing coucals, which are members of the cuckoo family. The giant coucal probably spent most of its time on the ground, feeding on insects, amphibians, and lizards. Perhaps only in emergencies, such as during an attack by a predator, would it take flight, likely in short, labored bursts—all its smallish wings could provide. This illustration shows the giant coucal in breeding (top) and nonbreeding plumage, though it's entirely speculative; no one knows the actual color of its plumage. Like so much about the vanished Australian megafauna, answers may lie in fossils still unfound, awaiting discovery and analysis by paleontologists.