Thylacine
The thylacine, also commonly known as the Tasmanian tiger or Tasmanian wolf, is an extinct species of carnivorous marsupial that was native to the Australian mainland and the islands of Tasmania and New Guinea. The thylacine died out in New Guinea and mainland Australia around 3,600–3,200 years ago, possibly because of the introduction of the dingo, whose earliest record dates to around the same time, but which never reached Tasmania. Prior to European settlement, around 5,000 remained in the wild on the island of Tasmania. Beginning in the nineteenth century, they were perceived as a threat to the livestock of farmers and bounty hunting was introduced. The last known of its species died in 1936 at Hobart Zoo in Tasmania. The thylacine is widespread in popular culture and is a cultural icon in Australia.
The thylacine was known as the Tasmanian tiger because of the dark transverse stripes that radiated from the top of its back, and it was called the Tasmanian wolf because it resembled a medium- to large-sized canid. The name thylacine is derived from meaning 'pouch' and -ine meaning 'pertaining to', and refers to the marsupial pouch. Both sexes had a pouch. The females used theirs for rearing young, and the males used theirs as a protective sheath, covering the external reproductive organs. The animal had a stiff tail and could open its jaws to an unusual extent. Recent studies and anecdotal evidence on its predatory behaviour suggest that the thylacine was a solitary ambush predator specialised in hunting small- to medium-sized prey. Accounts suggest that, in the wild, it fed on small birds and mammals. It was the only member of the genus Thylacinus and family Thylacinidae to have survived until modern times. Its closest living relatives are the other members of Dasyuromorphia, including the Tasmanian devil, from which it is estimated to have split 42–36 million years ago.
Intensive hunting on Tasmania is generally blamed for its extinction, but other contributing factors were disease, the introduction of and competition with dingoes, human encroachment into its habitat and climate change. The remains of the last known thylacine were discovered at the Tasmanian Museum and Art Gallery in 2022. Since extinction there have been numerous searches and reported sightings of live animals, none of which have been confirmed.
The thylacine has been used extensively as a symbol of Tasmania. The animal is featured on the official coat of arms of Tasmania. Since 1996, National Threatened Species Day has been commemorated in Australia on 7 September, the date on which the last known thylacine died in 1936. Universities, museums and other institutions across the world research the animal. Its whole genome sequence has been mapped, and there are efforts to clone and bring it back to life.
Taxonomic and evolutionary history
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 New Guinea and rare in Tasmania. Europeans may have encountered it in Tasmania 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".
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. He also sent a description of the thylacine in a letter to Joseph Banks, dated 30 March 1805.
The first detailed scientific description was made by Tasmania's Deputy Surveyor-General, George Harris, in 1808, five years after first European 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 maintain gender agreement with the genus name, 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, meaning "pouch" or "sack" and ine meaning "pertaining to". The name is pronounced or.
Evolution
The earliest records of the modern thylacine are from the Early Pleistocene, with the oldest known fossil record in southeastern Australia from the Calabrian age around 1.77–0.78 million years ago. Specimens from the Pliocene-aged Chinchilla Fauna, described as Thylacinus rostralis by Charles De Vis in 1894, have in the past been suggested to represent Thylacinus cynocephalus, but have been shown to either have been curatorial errors, or ambiguous in their specific attribution. The family Thylacinidae includes at least 12 species in eight genera. Thylacinids are estimated to have split from other members of Dasyuromorphia around 42–36 million years ago. The earliest representative of the family is Badjcinus turnbulli from the Late Oligocene of Riversleigh in Queensland, around 25 million years ago. Early thylacinids were quoll-sized, well under. It probably ate insects and small reptiles and mammals, although signs of an increasingly-carnivorous diet can be seen as early as the early Miocene in Wabulacinus. Members of the genus Thylacinus are notable for a dramatic increase in both the expression of carnivorous dental traits and in size, with the largest species, Thylacinus potens and Thylacinus megiriani, both approaching the size of a wolf. In late Pleistocene and early Holocene times, the modern thylacine was widespread throughout Australia and New Guinea.A classic 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 and New Guinea as canids did elsewhere, it developed many of the same features. Despite this, as a marsupial, it is unrelated to any of the Northern Hemisphere placental mammal predators.
Thylacinidae, including the thylacine, as the earliest divering lineage of Dasyuromorphia, which also includes numbats, dunnarts, and Dasyuridae The cladogram below follows the results of genetic studies:Phylogeny of Thylacinidae after Rovinsky et al.
Description
Descriptions of the thylacine come from preserved specimens, fossil records, skins and skeletal remains, and black and white photographs and film of the animal both in captivity and from the field. 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. The mature thylacine measured about in shoulder height and in body length, excluding the tail which measured around. Because the recorded body mass estimates are scant, it has been suggested that they may have weighed anywhere from, but a 2020 study that examined 93 adult specimens, with 40 of the specimens' sexes being known, argued that their average body mass would be with a range of based on volumetric analysis. There was slight sexual dimorphism, with the males being larger than females on average. Males weighed on average, and females on average weighed. The skull is noted to be highly convergent on those of canids, most closely resembling that of the red fox.Thylacines, uniquely for marsupials, had largely cartilaginous epipubic bones with a highly reduced osseous element. This was once considered a synapomorphy with sparassodonts, though it is now thought that both groups reduced their epipubics independently. 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 in length. Colouration varied from light fawn to a dark brown; the belly was cream-coloured.
Its rounded, erect ears were about long and covered with short fur. The early scientific studies suggested it possessed an acute sense of smell which enabled it to track prey, 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. In 2017, Berns and Ashwell published comparative cortical maps of thylacine and Tasmanian devil brains, showing that the thylacine had a larger, more modularised basal ganglion. The authors associated these differences with the thylacine's more predatory lifestyle. Analysis of the forebrain published in 2023 suggested that it was similar in morphology to other dasyuromorph marsupials and dissimilar to that of canids.
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, and had 46 teeth, but studies show the thylacine jaw was too weak to kill sheep. The tail vertebrae were fused to a degree, with resulting restriction of full tail movement. Fusion may have occurred as the animal reached full maturity. The tail tapered towards the tip. In juveniles, the tip of the tail had a ridge. 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 for protection.
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. 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.
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, 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. Some observers described it as 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.