The thylacine (/ˈθaɪləsiːn/ THY-lə-seen, or /ˈθaɪləsaɪn/ THY-lə-syne, also /ˈθaɪləsɪn/; Thylacinus cynocephalus) was the largest known carnivorous marsupial of modern times. It is commonly known as the Tasmanian tiger (because of its striped lower back) or the Tasmanian wolf (because of its canid-like appearance, traits and attributes). Native to continental Australia, Tasmania, and New Guinea, it is believed to have become extinct in the 20th century. It was the last extant member of its family, Thylacinidae; specimens of other members of the family have been found in the fossil record dating back to the late Oligocene.
Surviving evidence suggests that it was a relatively shy, nocturnal creature with the general appearance of a medium-to-large-size dog, except for its stiff tail and abdominal pouch (similar to a kangaroo) and dark transverse stripes that radiated from the top of its back, reminiscent of a tiger. The thylacine was an apex predator, like the tigers and wolves of the Northern Hemisphere from which it obtained two of its common names. As a marsupial, it was not closely related to these placental mammals, but because of convergent evolution it displayed a similar general form and adaptations. Its closest living relative is thought to be either the Tasmanian devil or the numbat. The thylacine was one of only two marsupials to have a pouch in both sexes (the other being the water opossum). The male thylacine had a pouch that presumably acted as a protective sheath, covering his external reproductive organs while he ran through thick brush. The thylacine has been described as a formidable predator.
The thylacine had become extremely rare or extinct on the Australian mainland before British settlement of the continent, but it survived on the island of Tasmania along with several other endemic species, including the Tasmanian devil. Intensive hunting encouraged by bounties is generally blamed for its extinction, but other contributing factors may have been disease, the introduction of dogs, and human encroachment into its habitat. Despite its official classification as extinct, sightings are still reported, though none have been confirmed.
Evolution
The modern thylacine probably appeared about 4 million years ago. Species of the family Thylacinidae 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 northwest Queensland. Dickson’s thylacine (Nimbacinus dicksoni) is the oldest of the seven discovered fossil species, dating back to 23 million years ago. This thylacinid was much smaller than its more recent relatives. The largest species, the powerful thylacine (Thylacinus potens) which grew to the size of a wolf, was the only species to survive into the late Miocene. In late Pleistocene and early Holocene times, the modern thylacine was widespread (although never numerous) throughout Australia and New Guinea.
An example of convergent evolution, the thylacine showed many similarities to the members of the dog family, Canidae, 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.
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
Discovery and taxonomy
Numerous examples of thylacine engravings and rock art have been found dating back to at least 1000 BC. 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 extinct in mainland Australia and rare in Tasmania. Europeans may have encountered it as far back as 1642 when Abel Tasman first arrived in Tasmania. His shore party reported seeing the footprints of “wild beasts having claws like a Tyger”. Marc-Joseph Marion du Fresne, arriving with the Mascarin in 1772, reported seeing a “tiger cat”. Positive identification of the thylacine as the animal encountered cannot be made from this report since the tiger quoll (Dasyurus maculatus) is similarly described. 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 D’Entrecasteaux. In 1805 William Paterson, the Lieutenant Governor of Tasmania, sent a detailed description for publication in the Sydney Gazette.
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 θύλακος (thýlakos), 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.
The thylacine was Australia’s largest predator 3500 years ago when dingoes were introduced by human settlers. The thylacine resembled a large, short-haired dog with a stiff tail which smoothly extended from the body in a way similar 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 15 to 20 distinctive dark stripes across its back, rump and the base of its tail, which earned the animal the nickname “tiger”. The stripes were more pronounced 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 (0.6 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.
The mature thylacine ranged from 100 to 130 cm (39 to 51 in) long, plus a tail of around 50 to 65 cm (20 to 26 in). Adults stood about 60 cm (24 in) at the shoulder and weighed 20 to 30 kg (40 to 70 lb). There was slight sexual dimorphism with the males being larger than females on average.
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.
The thylacine was able to open its jaws to an unusual extent: up to 80 degrees. This capability can be seen in part in David Fleay’s short black-and-white film sequence of a captive thylacine from 1933. The jaws were muscular but weak and had 46 teeth.
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 hindfeet were similar to the forefeet but had four digits rather than five. Their claws were non-retractable.
More detail can be seen in a cast taken from a freshly dead thylacine. The cast shows the plantar pad in more detail and shows that the plantar pad is tri-lobal in that it exhibits three distinctive lobes. It is a single plantar pad divided by three deep grooves. The distinctive plantar pad shape along with the asymmetrical nature of the foot makes it quite different from animals such as dogs or foxes. This cast dates back to the early 1930s and is part of the Museum of Victoria’s thylacine collection.
The early scientific studies suggested it possessed an acute sense of smell which enabled it to track prey,[40] but analysis of its brain structure revealed that its olfactory bulbs were not well developed. It is likely to have relied on sight and sound when hunting instead. Some observers described it having a strong and distinctive smell, others described a faint, clean, animal odour, and some no odour at all. It is possible that the thylacine, like its relative, the Tasmanian devil, gave off an odour when agitated.
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 fashion similar 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.
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.
Thylacines, uniquely for marsupials, have largely cartilaginous epipubic bones with a highly reduced osseous element. This has been once considered a synapomorphy with sparassodonts, though its now thought that both groups reduced their epipubics independently.
Unconfirmed sightings
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 several sources. On the mainland, sightings are most frequently reported in Southern Victoria.
Some sightings have generated a large amount of publicity. In 1973, Gary and Liz Doyle shot ten seconds of 8 mm film showing an unidentified animal running across and alongside a South Australian road. Attempts to positively identify the creature as a thylacine have been impossible due to the poor quality of the film. In 1982, a researcher with the Tasmania Parks and Wildlife Service, Hans Naarding, observed what he believed to be a thylacine for three minutes during the night at a site near Arthur River in northwestern Tasmania. The sighting led to an extensive year-long government-funded search. In 1985, Aboriginal tracker Kevin Cameron produced five photographs which appear to show a digging thylacine, which he stated he took in Western Australia.
In January 1995, a Parks and Wildlife officer reported observing a thylacine in the Pyengana region of northeastern Tasmania in the early hours of the morning. Later searches revealed no trace of the animal. In 1997, it was reported that locals and missionaries near Mount Carstensz in Western New Guinea had sighted thylacines. The locals had apparently known about them for many years but had not made an official report. In February 2005 Klaus Emmerichs, a German tourist, claimed to have taken digital photographs of a thylacine he saw near the Lake St Clair National Park, but the authenticity of the photographs has not been established. The photos were published in April 2006, fourteen months after the sighting. The photographs, which showed only the back of the animal, were said by those who studied them to be inconclusive as evidence of the thylacine’s continued existence. Due to the uncertainty of whether the species is still extant or not, the thylacine is sometimes regarded as a cryptid.
In 2008, a group of thylacines was purportedly captured on video in Victoria, but the veracity of the footage remains unconfirmed. In light of two detailed sightings around 1983 from the remote Cape York Peninsula of mainland Australia, scientists led by Bill Laurance announced plans in 2017 to survey the area for thylacines using camera traps.
