| Thylacine - Thylacinus cynocephalus | |
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| Cynocephalus | Jun 20 2018, 06:07 PM Post #1 |
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Thylacine - Thylacinus cynocephalus![]() Kingdom: Animalia Phylum: Chordata Class: Mammalia Infraclass: Marsupialia Order: Dasyuromorphia Family: †Thylacinidae Genus: †Thylacinus Species: †T. cynocephalus Biology: The Thylacine (Thylacinus cynocephalus: dog-headed pouched-dog) is a large carnivorous marsupial now believed to be extinct. It was the only member of the family Thylacinidae to survive into modern times. It is also known as the Tasmanian Tiger or Tasmanian Wolf. he modern thylacine first 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.[16][17] 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.[18] 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.[19] In late Pleistocene and early Holocene times, the modern thylacine was widespread (although never numerous) throughout Australia and New Guinea.[20] 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.[21] Size: The Thylacine was sandy yellowish-brown to grey in colour and had 15 to 20 distinct dark stripes across the back from shoulders to tail. Although the large head was dog- or wolf-like, the tail was stiff and the legs were relatively short. Body hair was dense, short and soft, to 15mm in length. It had short ears (about 80 mm long) that were erect, rounded and covered with short fur. Jaws were large and powerful and there were 46 teeth. Adult male Thylacine were larger on average than females. The female Thylacine had a back-opening pouch. The litter size was up to four and the young were dependent on the mother until at least half-grown. Interestingly, males also had a back-opening, partial pouch. 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.[31] 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.[21] 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 pronounced in younger specimens, fading as the animal got older.[32] 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.[33] Colouration varied from light fawn to a dark brown; the belly was cream-coloured.[34]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).[35] Adults stood about 60 cm (24 in) at the shoulder and weighed 20 to 30 kg (40 to 70 lb).[35] There was slight sexual dimorphism with the males being larger than females on average Prey,Competition and Extinction: The Thylacine was mainly nocturnal or semi-nocturnal but was also out during the day. The animal moved at a slow pace, generally stiff in its movements. The Thylacine hunted singly or in pairs and mainly at night.Thylacines preferred kangaroos and other marsupials, small rodents and birds. They were reported to have preyed on sheep and poultry after European colonisation, although the extent of this was almost certainly exaggerated. For example, a famous photo is now known to have been staged using a taxidermied Thylacine specimen with a dead chicken placed in its mouth. Although there are methods that can be used to identify the diet and feeding behavior of thylacine, findings and theories on this subject remain hotly debated.[57] A study published in 2011 yields some insight: "Dental and biogeochemical evidence suggests that T. cynocephalus was a hypercarnivore restricted to eating vertebrate flesh"[57] The thylacine was exclusively carnivorous. Its stomach was muscular, and could 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.[32] Analysis of the skeletal frame and observations of it in captivity suggest that it preferred to single out a target animal and pursue that animal 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.[26] Trappers reported it as an ambush predator.[32]Little is known of the thylacine's diet and feeding behaviour. Prey is believed to have included kangaroos, wallabies and wombats, birds and small animals such as potoroos and possums. One prey animal may have been the once common Tasmanian emu.[58] The emu was a large, flightless bird which shared the habitat of the thylacine and was hunted to extinction around 1850, possibly coinciding with the decline in thylacine numbers.[59] Both dingoes and foxes have been noted to hunt the emu on the mainland.[60][61] European settlers believed the thylacine to prey upon farmers' sheep and poultry.[62][63] Throughout the 20th century, the thylacine was often characterised as primarily a blood drinker; according to Robert Paddle, the story's popularity seems to have originated from a single second-hand account heard by Geoffrey Smith (1881–1916)[64][65][66] in a shepherd's hut.[67] In captivity, thylacines were fed a wide variety of foods, including dead rabbits and wallabies as well as beef, mutton, horse, and occasionally poultry.[68] Tasmania's leading naturalist Michael Sharland published an article in 1957 stating that a captive thylacine refused to eat dead wallaby flesh or to kill and eat a live wallaby offered to it, but "ultimately it was persuaded to eat by having the smell of blood from a freshly killed wallaby put before its nose."[69]A 2011 study by the University of New South Wales using advanced computer modelling indicated that the thylacine had surprisingly feeble jaws. Animals usually take prey close to their own body size, but an adult thylacine of around 30 kilograms (66 lb) was found to be incapable of handling prey much larger than 5 kilograms (11 lb). Researchers believe thylacines only ate small animals such as bandicoots and possums, putting them into direct competition with the Tasmanian devil and the tiger quoll. Such specialisation probably made the thylacine susceptible to small disturbances to the ecosystem.[39][70]Although the living grey wolf is widely seen as the thylacine's counterpart, a recent study proposes that thylacine was more of an ambush predator as opposed to a pursuit predator. In fact, the predatory behaviour of the thylacine was probably closer to ambushing felids than to large pursuit canids. Consequently, at least in terms of the postcranial anatomy, the vernacular name of "Tasmanian tiger" may be more apt than "marsupial wolf".At one time the Thylacine was widespread over continental Australia, extending north to New Guinea and south to Tasmania. In recent times it was confined to Tasmania where its presence has not been established conclusively for more than seventy years. In Tasmania the species was best known from the north and east coast and midland plains region rather than from the mountains of the south-west. lthough the thylacine was extinct on mainland Australia, it survived into the 1930s on the island state of Tasmania. At the time of the first European settlement, the heaviest distributions were in the northeast, northwest and north-midland regions of the state.[50] They were rarely sighted during this time 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 (the equivalent of £100 or more today) for dead adult thylacines and ten shillings for pups. In all they paid out 2,184 bounties, but it is thought that many more thylacines were killed than were claimed for.[40] Its extinction is popularly attributed to these relentless efforts by farmers and bounty hunters.[40] It is likely that multiple factors led to its decline and eventual extinction, including competition with wild dogs introduced by European settlers,[81] erosion of its habitat, the concurrent extinction of prey species, and a distemper-like disease that also affected many captive specimens at the time.[34][82] Whatever the reason, the animal had become extremely rare in the wild by the late 1920s. Despite the fact that the thylacine was believed by many to be responsible for attacks on sheep, in 1928 the Tasmanian Advisory Committee for Native Fauna recommended a reserve similar to the Savage River National Park to protect any remaining thylacines, with potential sites of suitable habitat including the Arthur-Pieman area of western Tasmania.[83] n 2017, Berns and Ashwell published comparative cortical maps of thylacine and Tasmanian devil brains, showing that the thylacine had a larger, more modularized basal ganglion. The authors associated these differences with the thylacine's predatory lifestyle.[128] The same year, White, Mitchell and Austin published a large-scale analysis of thylacine mitochondrial genomes, showing that they had split into Eastern and Western populations on the mainlaind prior to the Last Glacial Maximum and had low genetic diversity by the time of European arrival.[129] Although the precise reasons for extinction of the Thylacine from mainland Australia are not known it appears to have declined as a result of competition with the Dingo and perhaps hunting pressure from humans. The Thylacine became extinct on the Australian mainland not less than 2000 years ago. Its decline and extinction in Tasmania was probably hastened by the introduction of dogs, but appears mainly due to direct human persecution as an alleged pest. Aboriginal rock-paintings of Thylacine-like animals are recognised from northern Australia including the Kimberley region of Western Australia. They have also been found on walls or overhangs on exposed rock surfaces in the Upper East Alligator region of Deaf Adder Creek and Cadell River crossing in the Northern Territory. There is evidence to suggest that Aboriginal people in Tasmania used the Thylacine as a food item.Fossil thylacines have been reported from Victoria, South Australia, Western Australia and Queensland.Work at the Riversleigh World Heritage fossil site in north-west Queensland has unearthed a spectacular array of thylacines dating from about 30 million years ago to almost 12 million years ago. At least seven different species are present, ranging from small specialised cat-sized individuals to fox-sized predators.The most spectacular find has been an almost complete skeleton of a thylacine from the AL90 site at Riversleigh. First glimpsed in 1996 when a limestone boulder was cracked to reveal part of the skull after 17 million years in a limestone tomb. After many months of intricate preparation the skeleton has been reassembled. The fossil record of thylacines is a powerful reminder of how important it is to learn from the past the messages for the future. In Riversleigh times there were several species but by 8 million years ago only one species remained, the Powerful Thylacine, Thylacinus potens.The modern Thylacine made its appearance about 4 million years ago.A mummified carcass of a Thylacine has been found in a cave on the Nullabor Plain. It lived about 4 to 5,000 years ago, just before the Dingo was introduced into Australia. Edited by Ferreomus, Jun 20 2018, 06:22 PM.
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