Thylacine

Name and taxonomy

George Harris wrote the first scientific description in 1808 and placed the animal among the American opossums, as Didelphis cynocephala. The species name means dog-headed. Temminck created the genus Thylacinus in 1824, from the Greek word for a pouch. The common name thylacine comes straight from the genus. Both sexes had a pouch: the female used hers for her young, and the male's sheathed his reproductive organs.

Settlers in the 1800s knew it as the zebra wolf, the zebra opossum or simply the hyena. The Australian National Dictionary lists 11 informal names for it. Tasmanian Aboriginal names included coorinna, kanunnah, loarinna and lagunta. In Palawa kani, the revived Tasmanian language, it is kaparunina. The thylacine was the only member of its family, Thylacinidae, to survive into modern times.

Evolution and relatives

Thylacinids split from the other dasyuromorph marsupials, such as the Tasmanian devil and the quolls, about 42 to 36 million years ago. The family held at least 12 species in eight genera. The earliest, Badjcinus turnbulli, lived at Riversleigh in Queensland about 25 million years ago and was the size of a quoll. Later species in the genus Thylacinus grew larger and more carnivorous, and two approached the size of a wolf. The oldest fossils of the modern species come from south-eastern Australia and date to about 1.77 to 0.78 million years ago.

The thylacine is a textbook case of convergent evolution. It filled the niche that dogs and wolves fill elsewhere, so it evolved sharp teeth, strong jaws, raised heels and a dog-like body. Its skull most closely resembled that of the red fox. Genetic work in 2019 and 2021 traced some of that likeness to shared changes in the genes that shape the skull bones. Yet it was a marsupial, and it was probably no closer to a wolf than a kangaroo is.

Appearance

The thylacine resembled a big dog with short hair and a stiff tail that ran smoothly out of the body, as in a kangaroo. It stood about 60 centimetres at the shoulder. The head and body measured 100 to 130 cm, and the tail added 50 to 65 cm. Adults weighed 9.8 to 28.1 kilograms, and the average was about 16.7 kg. Males averaged 19.7 kg and females 13.7 kg.

The coat was yellow-brown, from light fawn to dark brown, with a cream belly. Between 15 and 20 dark stripes crossed the back, the rump and the base of the tail. The stripes were boldest in young animals and faded with age. The hair was dense and soft, and it grew up to 15 millimetres long. The rounded ears stood erect and measured about 8 cm.

The jaws held 46 teeth and could open to about 80 degrees. The claws did not retract, and the hind foot had four toes to the front foot's five. The female's pouch opened to the rear and held four teats. The male had a scrotal pouch, which no other Australian marsupial has.

Habitat and range

Rock art shows that the thylacine once lived across mainland Australia and New Guinea. A dried carcass found in a Nullarbor cave in 1990 was about 3,300 years old. The northernmost record comes from a rock shelter in the highlands of Papua New Guinea, dated to about 10,000 to 8,500 years ago. On the mainland it probably favoured dry eucalyptus forest, wetlands and grassland.

In the 1800s the species probably lived across the whole of Tasmania. It was most common in the drier open country and woodland of the Midlands, the East Coast, the Central Highlands and the North West. It also lived in mountains and rainforest, but scarce prey kept numbers low there. Capture records suggest it had gone from eastern Tasmania by the 1920s. The last four small populations held on in the west in the 1930s, mostly around the Arthur and Pieman rivers.

A home range covered about 40 to 80 square kilometres. The animal kept to its range but did not seem to defend it, and groups larger than a family were sometimes seen. By day it rested in a small cave or hollow log, on a bed of fern, bark or twigs.

Diet and hunting

The thylacine was the largest marsupial carnivore of its time and an apex predator. Historical accounts name small mammals and birds as its food. The red-necked wallaby was the mammal most often recorded, along with the pademelon, the echidna, bandicoots and possums. Waterbirds such as ducks, teal, coots and native hens were the birds most often taken, and black swans were probable prey. Once European rabbits spread across Tasmania, thylacines ate those too.

Settlers blamed it for sheep and poultry losses, but the historian Robert Paddle found little evidence for the charge. Feral dogs probably killed most of the sheep. The tale that it drank blood grew from one second-hand story heard in a shepherd's hut. A 1921 photograph of a thylacine with a chicken fixed its reputation, yet the animal was captive and may have been dead and posed.

Modern studies agree that its jaws were weak for its size. Computer modelling in 2011 found that a 30 kg thylacine could not handle prey much over 5 kg. Skull shape points to prey under 45% of its own weight, the pattern seen in living carnivores under 21 kg. Trappers described an ambush hunter that worked alone or in pairs at night, and the elbow joint supports that view. Its stomach could stretch to hold a large meal after a long hungry spell.

Behaviour and social life

The thylacine hunted at night and at dusk, and it slept through the day. It withdrew to hills and forest for shelter and came out to hunt on open heath after dark. Observers called it shy and secretive, though sometimes curious. It was mostly solitary, but pairs and small family groups were reported.

Its gait was stiff and awkward, and it could not run fast. When alarmed it could hop on its hind legs like a kangaroo, and captive animals showed this many times. It could also balance upright on its hind legs for short periods. In 1863 a captive female jumped to the rafters of her cage, about 2 metres up.

Captive animals paid little attention to their keepers and seemed dazzled by bright sunlight. They retreated into inner dens during the brightest hours, yet they sometimes came out to bask. A sleeping thylacine lay stretched on its side with the upper ear held erect. Trapped animals were docile, and many died soon after capture, probably from shock.

Communication and senses

When agitated the thylacine growled and hissed, often with a wide threat yawn. While hunting it gave a fast series of guttural, cough-like barks, written down as yip-yap or hop-hop-hop. Those barks probably kept the members of a family group in touch. A long whining cry may have identified an animal at a distance, and a low snuffle passed between family members.

Early naturalists credited it with a keen nose, but its olfactory bulbs turn out to have been small. It probably hunted by sight and sound instead. The muzzle carried about 24 whiskers. Some observers reported a strong smell and others none, so it may have released an odour only when agitated, like the Tasmanian devil.

Reproduction and life cycle

Bounty records show pouch young in every month, so some breeding went on all year. The peak came in winter and spring. Guiler estimated a breeding season of about four months, and a female may have raised a second litter after the first was weaned. Only one pair of adults was ever caught together, which suggests the sexes met only to mate. The species bred in captivity only once, at Melbourne Zoo in 1899.

A litter held up to four joeys, usually two or three. The mother carried them in her rear-opening pouch for up to three months. Pouch young were born hairless and blind, but they left the pouch furred and with their eyes open. A joey's own pouch became visible at 9.5 weeks. After leaving the pouch the young stayed in the lair while the mother hunted, until they could follow her. She protected them until they were at least half grown.

Life expectancy in the wild was probably 5 to 7 years. Animal Diversity Web gives the captive record as a female of about 12.6 years, who spent 9.5 of them in a zoo. Only 11 preserved pouch young exist in museums, and a 2018 CT study used them to trace growth in the pouch.

Predators and threats

As the top predator of its island, the adult thylacine had no natural enemies. On the mainland it vanished about 3,200 years ago, at the same time as the Tasmanian devil and soon after the dingo arrived. The dingo hunted in packs, had a sturdier skull and ate a wider diet, so it probably outcompeted the thylacine. A 2013 study added human population growth, new technology and a sharp climate shift as larger factors.

In Tasmania the threats were human. The Van Diemen's Land Company paid bounties from 1830. Between 1888 and 1909 the government paid £1 for an adult and ten shillings for a pup, and it paid out more than 2,200 bounties. Many more animals were killed than claimed. Wild dogs, habitat clearance, falling prey numbers and low genetic diversity all added pressure. A distemper-like illness, probably introduced around 1896, cut lifespans and killed pups as it spread from east to west.

Population and conservation

The IUCN lists the thylacine as Extinct. Before Europeans arrived, Tasmania held perhaps 2,000 to 4,000 animals, or as many as 5,000 by one estimate. Numbers crashed after 1905, and fewer than 700 to 800 remained when the bounty ended in 1909. By the 1920s the species was vanishingly rare.

Wilf Batty shot the last wild thylacine known to be killed, in 1930 at Mawbanna. The last reliably dated wild capture was a young male in 1931. Legal protection came on 10 July 1936, just 59 days before the last captive animal died. The IUCN declared it extinct in 1982 and the Tasmanian government in 1986, after 50 years without a confirmed record. CITES removed it from Appendix I in 2013.

More money has gone into searching for the thylacine than for any other mammal. The most intensive search ran from 1967 to 1973 and found nothing. Ted Turner offered $100,000 in 1983, and The Bulletin offered $1.25 million in 2005, and nobody claimed either. Museums in 23 countries hold 756 specimens.

Relationship with humans

Aboriginal Australians carved and painted the thylacine from at least 1000 BC, and petroglyphs survive on the Burrup Peninsula. Abel Tasman's crew reported clawed footprints in 1642, and French explorers made the first firm record on 13 May 1792. Settlers saw a sheep killer and a poultry thief, and newspapers called it vermin and a savage brute. Trappers earned a living from the bounty, and zoos as far away as New York bought live animals.

Captive thylacines were docile, and the few recorded bites came from startled or cornered animals. David Fleay was bitten on the buttock while he filmed the last captive animal in 1933. His 45-second film, colourised in 2021, is the best-known record of the species. Since 1996 Australia has marked National Threatened Species Day on 7 September, the day the last thylacine died. In 2022 the University of Melbourne and Colossal Biosciences announced a plan to recreate the species from the fat-tailed dunnart, which other scientists doubt.

In culture and myth

A Nuenonne story tells how a thylacine pup saved the spirit boy Palana from a giant kangaroo. Palana painted the pup's back with ochre for its bravery, and that gave the species its stripes. A constellation near Gemini, Wurrawana Corinna, marked the deed. An early European record says Aboriginal people blamed bad weather on a thylacine carcass left uncovered on the ground.

The thylacine sits on the Tasmanian coat of arms, on the state government logo and, since 1998, on the number plates. John Gould's plates from The Mammals of Australia are the most copied images, and Cascade Brewery put one on its label in 1987. In 1968 a man who falsely claimed to be a zoo curator invented the name Benjamin for the last animal. The myth still circulates. The species stars in the video game Ty the Tasmanian Tiger, the film The Hunter and the series The Peripheral. For the artist Gordon Hookey it stands for the harm done to First Nations peoples, and for others it is a symbol of hope.