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Australian Fauna


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Tasmanian Tiger
Thylacinus cynocephalus


Thylacine - Tasmanian tiger



The Thylacine, Thylacinus cynocephalus (Latin: wolf-headed pouched dog), was the largest known carnivorous marsupial of modern times. Native to Australia and New Guinea, it is thought to have become extinct in the 20th century. It is commonly known as the Tasmanian tiger, the Tasmanian wolf and, colloquially, the Tassie (or Tazzy) tiger or simply The Tiger. It was the last extant member of its genus, Thylacinus, although several related species have been found in the fossil record dating back to the early Miocene.

The modern Thylacine first appeared about 4 million years ago. Species of the Thylacinidae family date back to the beginning of the Miocene; since the early 1990s, at least seven fossil species have been uncovered at Riversleigh, part of Lawn Hill National Park in north-west Queensland. Dickson's Thylacine (Nimbacinus dicksoni), is the oldest of the seven discovered fossil species, dating back to 23 million years ago. This early thylacinid was much smaller than its more recent relatives. In late Pleistocene and early Holocene times, the modern Thylacine was widespread (although never numerous) throughout Australia and New Guinea.

Discovery and taxonomy

The indigenous peoples of Australia made first contact with the Thylacine. Numerous examples of Thylacine engravings and rock art have been found dating back to at least 1000 BCE. Petroglyph images of the Thylacine can be found at the Dampier Rock Art Precinct on the Burrup Peninsula in Western Australia. By the time the first European explorers arrived, the animal was already rare in Tasmania. The first definitive encounter was by French explorers on 13 May 1792, as noted by the naturalist Jacques Labillardière, in his journal from the expedition led by 'Entrecasteaux. However, it was not until 1805 that William Paterson, the Lieutenant Governor of Tasmania, sent a detailed description for publication in the Sydney Gazette and New South Wales Advertiser.

The first detailed scientific description was made by Tasmania's Deputy Surveyor-General, George Harris in 1808, five years after first settlement of the island. Harris originally placed the Thylacine in the genus Didelphis<, which had been created by Linnaeus for the American opossums, describing it as Didelphis cynocephala, the "dog-headed opossum". Recognition that the Australian marsupials were fundamentally different from the known mammal genera led to the establishment of the modern classification scheme, and in 1796 Geoffroy Saint-Hilaire created the genus Dasyurus where he placed the Thylacine in 1810. To resolve the mixture of Greek and Latin nomenclature the species name was altered to cynocephalus. In 1824, it was separated out into its own genus, Thylacinus, by Temminck. The common name derives directly from the genus name, originally from the Greek thylakos, meaning pouch or sack.

Description

Descriptions of the Thylacine vary, as evidence is restricted to preserved joey specimens; fossil records; skins and skeletal remains; black and white photographs and film of the animal in captivity; and accounts from the field.

An example of convergent evolution, the Thylacine showed many similarities to the members of the Canidae (dog) family of the Northern Hemisphere: sharp teeth, powerful jaws, raised heels and the same general body form. Since the Thylacine filled the same ecological niche in Australia as the dog family did elsewhere, it developed many of the same features. Despite this, it is unrelated to any of the Northern Hemisphere predators.

The Thylacine resembled a large, short-haired dog with a stiff tail which smoothly extended from the body in a similar way to that of a kangaroo. Many European settlers drew direct comparisons with the hyena, because of its unusual stance and general demeanour. Its yellow-brown coat featured 13 to 21 distinctive dark stripes across its back, rump and the base of its tail, which earned the animal the nickname, "Tiger". The stripes were more marked in younger specimens, fading as the animal got older. One of the stripes extended down the outside of the rear thigh. Its body hair was dense and soft, up to 15 mm (0.59 in) in length; in juveniles the tip of the tail had a crest. Its rounded, erect ears were about 8 cm (3.1 in) long and covered with short fur. Colouration varied from light fawn to a dark brown; the belly was cream-coloured.

They are easy to tell from a true dog because of the stripes on the back but the skeleton is harder to distinguish. Zoology students at Oxford had to identify 100 zoological specimens as part of the final exam. Word soon got around that, if ever a 'dog' skull was given, it was safe to identify it as Thylacinus on the grounds that anything as obvious as a dog skull had to be a catch. Then one year the examiners, to their credit, double bluffed and put in a real dog skull. The easiest way to tell the difference is by the two prominent holes in the palate bone, which are characteristic of marsupials generally.

– Richard Dawkins, The Ancestor's Tale

The mature Thylacine ranged from 100 cm (39 in) to 180 cm (71 in) long, including a tail of around 50 cm (20 in) to 65 cm (26 in). The largest measured specimen was 290 cm (9.5 ft) from nose to tail. Adults stood about 60 cm (24 in) at the shoulder and weighed 20 kg (44 lb) to 30 kg (66 lb). There was slight sexual dimorphism with the males being larger than females on average. The Thylacine's jaws were muscular and powerful and were lined with 46 teeth. It could also open the mouth to an unusual extent: up to 120 degrees.

The female Thylacine had a pouch with four teats, but unlike many other marsupials, the pouch opened to the rear of its body. Males had a scrotal pouch, unique amongst the Australian marsupials, into which they could withdraw their scrotal sac.

Thylacine footprints could be distinguished from other native or introduced animals; unlike foxes, cats, dogs, wombats or Tasmanian Devils, Thylacines had a very large rear pad and four obvious front pads, arranged in almost a straight line. The hind feet were similar to the forefeet but had four digits rather than five. Their claws were non-retractable.

The Thylacine was noted as having a stiff and somewhat awkward gait, making it unable to run at high speed. It could also perform a bipedal hop, in a similar fashion to a kangaroo—demonstrated at various times by captive specimens. Guiler speculates that this was used as an accelerated form of motion when the animal became alarmed. The animal was also able to balance on its hind legs and stand upright for brief periods.

Although there are no recordings of Thylacine vocalisations, observers of the animal in the wild and in captivity noted that it would growl and hiss when agitated, often accompanied by a threat-yawn. During hunting it would emit a series of rapidly repeated guttural, cough-like barks (described as "yip-yap", "cay-yip" or "hop-hop-hop"), probably for communication between the family pack members. It also had a long, whining cry, probably for identification at distance, and a low snuffling noise used for communication between family members.

Ecology and behaviour

Little is known about the behaviour or habitat of the Thylacine. A few observations were made of the animal in captivity, but only limited, anecdotal evidence exists of the animal's behaviour in the wild. Most observations were made during the day whereas the Thylacine was naturally nocturnal. Those observations made in the 20th century may have been atypical as they were of a species already under the stresses that would soon lead to its extinction. Some behavioural characteristics have been extrapolated from the behaviour of its close relative, the Tasmanian devil.

The Thylacine probably preferred the dry eucalyptus forests, wetlands, and grasslands in continental Australia. Indigenous Australian rock paintings indicate that the Thylacine lived throughout mainland Australia and New Guinea. Proof of the animal's existence in mainland Australia came from a desiccated carcass that was discovered in a cave in the Nullarbor Plain in Western Australia in 1990; carbon dating revealed it to be around 3,300 years old.

In Tasmania it preferred the woodlands of the midlands and the coastal heath, which eventually became the primary focus of British settlers seeking grazing properties for their livestock. The striped pattern may have provided camouflage in woodland conditions, but it may have also served for identification purposes. The animal had a typical home range of between 40 sq km (15 sq mi) and 80 sq km (31 sq mi). It appears to have kept to its home range without being territorial; groups too large to be a family unit were sometimes observed together.

The Thylacine was a nocturnal and crepuscular hunter, spending the daylight hours in small caves or hollow tree trunks in a nest of twigs, bark or fern fronds. It tended to retreat to the hills and forest for shelter during the day and hunted in the open heath at night. Early observers noted that the animal was typically shy and secretive, with awareness to the presence of humans and generally avoiding contact, though it occasionally showed inquisitive traits.

There is evidence for at least some year-round breeding (cull records show joeys discovered in the pouch at all times of the year), although the peak breeding season was in winter and spring. They would produce up to four cubs per litter (typically two or three), carrying the young in a pouch for up to three months and protecting them until they were at least half adult size. Early pouch young were hairless and blind, but they had their eyes open and were fully furred by the time they left the pouch. After leaving the pouch, and until they were developed enough to assist, the juveniles would remain in the lair while the female hunted. Thylacines only once bred successfully in captivity, in Melbourne Zoo in 1899. Their life expectancy in the wild is estimated to have been 5 to 7 years, although captive specimens survived up to 9 years.

Diet

The Thylacine was exclusively carnivorous. Its stomach was muscular with an ability to distend to allow the animal to eat large amounts of food at one time, probably an adaptation to compensate for long periods when hunting was unsuccessful and food scarce. Analysis of the skeletal frame and observations of the Thylocine in captivity point to it singling out a target animal and pursuing its prey until it was exhausted. Some studies conclude that the animal may have hunted in small family groups, with the main group herding prey in the general direction of an individual waiting in ambush. Trappers reported it as an ambush predator.

Prey included kangaroos, wallabies, wombats, birds and small animals such as potoroos and possums. A favourite prey animal may have been the once-common Tasmanian emu, a large, flightless bird which shared the habitat of the Thylacine. It was hunted to extinction around 1850, possibly coinciding with the decline in Thylacine numbers. Both dingos and foxes have been noted to hunt the emu on the mainland. European settlers believed the Thylacine to have preyed upon farmers' sheep and poultry. In captivity, Thylacines were fed a wide variety of foods, including dead rabbits and wallabies as well as beef, mutton, and horse and occasionally poultry.

Extinction

The Thylacine is likely to have become extinct in mainland Australia about 2,000 years ago (possibly earlier in New Guinea). The extinction is attributed to competition from indigenous humans and invasive ding os. Doubts exist over the impact of the dingo, however, as the two species would not have been in direct competition with one another. The dingo is a primarily diurnal predator, while it is thought the Thylacine hunted mostly at night. In addition, the Thylacine had a more powerful build, which would have given it an advantage in one-on-one encounters. However, recent morphological examinations on dingo and thylacine skulls by Stephen Wroe of the University of NSW biomechanics show that although the dingo had a weaker bite, it's skull could resist greater stresses, allowing it to pull down larger prey than the thylacine. The thylacine was also much less versatile in diet than the omnivorous dingo.

Rock paintings from the Kakadu National Park clearly show that Thylacines were hunted by early humans, and it is believed that dingos and Thylacines may have competed for the same prey. Their environments clearly overlapped: Thylacine sub-fossil remains have been discovered in proximity to those of dingos. The adoption of the dingo as a hunting companion by the indigenous peoples would have put the Thylacine under increased pressure.

Although long extinct on the Australian mainland by the time the European settlers arrived, the Thylacine survived into the 1930s in Tasmania. At the time of the first settlement, the heaviest distributions were in the northeast, northwest and north-midland regions. From the early days of European settlement they were rarely sighted but slowly began to be credited with numerous attacks on sheep. This led to the establishment of bounty schemes in an attempt to control their numbers. The Van Diemen's Land Company introduced bounties on the Thylacine from as early as 1830, and between 1888 and 1909 the Tasmanian government paid £1 per head for the animal (10 shillings for pups). In all they paid out 2,184 bounties, but it is thought that many more Thylacines were killed than were claimed. Its extinction is popularly attributed to these relentless efforts by farmers and bounty hunters. However, it is likely that multiple factors led to its decline and eventual extinction, including competition with wild dogs (introduced by settlers), erosion of habitat, the concurrent extinction of prey species, and a distemper-like disease that also affected many captive specimens at the time.

Whatever the reason, the animal had become extremely rare in the wild by the late 1920s. There were several efforts to save the species from extinction. Records of the Wilsons Promontory management committee dating to 1908 included recommendations for Thylacines to be reintroduced to several suitable locations on the Victorian mainland. In 1928, the Tasmanian Advisory Committee for Native Fauna had recommended a reserve to protect any remaining Thylacines, with potential sites of suitable habitat including the Arthur-Pieman area of western Tasmania.

The last known wild Thylacine to be killed was shot in 1930, by farmer Wilf Batty in Mawbanna, in the northeast of the state. The animal (believed to be a male) had been seen around Batty's hen houses for several weeks.

The Thylacine held the status of "endangered species" until 1986. International standards state that any animal for which no specimens have been recorded for 50 years is to be declared extinct. Since no definitive proof of the Thylacine's existence had been found since1936, it met that official criterion and was declared officially extinct by the International Union for Conservation of Nature. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is more cautious, listing it as "possibly extinct".

Although the Thylacine is considered extinct, many people believe the animal still exists. Sightings are regularly claimed in Tasmania, other parts of Australia and even in the Western New Guinea area of Indonesia, near the Papua New Guinea border. The Australian Rare Fauna Research Association reports having 3,800 sightings on file from mainland Australia since the 1936 extinction date, while the Mystery Animal Research Centre of Australia recorded 138 up to 1998, and the Department of Conservation and Land Management recorded 65 in Western Australia over the same period. Independent Thylacine researchers Buck and Joan Emburg of Tasmania report 360 Tasmanian and 269 mainland post-extinction 20th century sightings, figures compiled from a number of sources. On the mainland, sightings are most frequently reported in Southern Victoria.

Cultural references

The Thylacine has been used extensively as a symbol of Tasmania. The animal is featured on the official Tasmanian Coat of Arms. It is used in the official logos of Tourism Tasmaniaand the Launceston City Council. Since 1998 it has been prominently displayed on Tasmanian vehicle number plates

The plight of the Thylacine was featured in a campaign for The Wilderness Society, entitled We Used to Hunt Thylacines. The animal is featured on Cascade Brewery beer products and in their television advertisements. In video games, Ty the Tasmanian Tiger is the star of his own trilogy. In the early 1990s' cartoon TV show "Taz-Mania" the character, Wendell T. Wolf, was supposedly the last surviving Tasmanian wolf. Tiger Tale is a children's book based on an Aboriginal myth about how the Thylacine got its stripes. The Thylacine is the mascot for the Tasmanian Tigers state cricket team and has also appeared in postage stamps from Australia, Equatorial Guinea, and Micronesia.

  

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