Thylacine

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Thylacine
Thylacine1.jpg
Scientific classification
Kingdom Information
Domain Eukaryota
Kingdom Animalia
Subkingdom Bilateria
Branch Deuterostomia
Phylum Information
Phylum Chordata
Sub-phylum Vertebrata
Infraphylum Gnathostomata
Class Information
Superclass Tetrapoda
Class Mammalia
Sub-class Theria
Infra-class Marsupialia
Order Information
Superorder Eometatheria
Order Dasyuromorphia
Family Information
Family Thylacinidae
Genus Information
Genus Thylacinus
Species Information
Species T. cynocephalus
Population statistics
Conservation status Extinct[1]

The thylacine (Thylacinus cynocephalus) is an extinct species of marsupial, and the largest carnivorous mammal which lived in Australia into modern times. Once common on the Australian mainland, it disappeared there some 2,000 years ago, leaving the island of Tasmania as a last stand where severe persecution reduced its numbers to a last known survivor dying in a zoo in 1936[2]. Since then the thylacine has become a subject of cryptozoology as well as scientific attempts to clone the animal with the possibility of bringing it back from extinction.

Etymology

European settlers arriving on Tasmania in the early 19th century gave the animal its two most familiar names: Tasmanian wolf, in reference to its wolf-like appearance, and Tasmanian tiger for the tiger-like stripes on the body; it is still commonly referred to as the tiger on the island today. "Ka-nunnah", "laoonana", "langunta", "cab-berr-­one-­nen", and "corinna" were just several of many names given to the thylacine by Tasmanian aborigines[3]. The binomial name comes from from the Greek θύλακος (thýlakos; "sack" or "pouch") and the Latin ­cynocephalus ("dog-head")[4].

Description

The thylacine had a body length of 39 to 51 inches, a tail length of 20 to 26 inches, and a weight of 40 to 70 pounds. The shoulder height was about 24 inches. The fur was short and rough, tan to yellow-brown in color, and from just behind the shoulder blades to the base of the tail it bore 13 to 19 black-brown transverse stripes, resulting in the "tiger" name. The only other color was a small amount of white around the eyes and ears. The thylacine showed amazing similarities with some carnivores from the Canidae family, with a somewhat wider skull bearing 46 teeth. Similar to dogs, the canines were long and sharp; additionally the gape of the mouth was very wide, which could open up to 80 degrees. The limbs were rather short, the legs each ended in five toes. The animals were not very fast runners, reaching a speed of up to 24 mph, far less than comparably-sized dogs; film of captive specimens indicate it was somewhat kangaroo-like on his hind legs, with the tail serving as a support. Like other marsupials it carried its young in a pouch, which opened towards the rear.

"Benjamin" at the Hobart Zoo, Tasmania, 1933; note the extremely wide gape of the mouth.

Prior to the extinction thylacines were not fully studied; most observations on their habits came from captive zoo animals. They were usually nocturnal, but were sometimes observed during daylight. It was a solitary animal, but sometimes hunted in pairs or small groups. It made several sounds: a dull barking during the hunt, a growling when angry, and a whine, which presumably served to communicate with other thylacines. It has been claimed they were stamina hunters, i.e. pursuing prey until they tired out and were killed by the thylacine's powerful bite; certainly this factor has garnered a reputation of being a sheep-killer resulting in the 19th to early-20th century persecution. Recent investigations by a team led by Marie Attard from the University of New South Wales in Sydney have painted a different story. Using computer models and jaw comparisons with other predators, she has determined that the thylacine had a relatively-weak bite; a sheep would have been an impossible kill. This, plus the animal's slow speed - it was a persevering runner - meant that it went after small prey such as wallabies, bandicoots, and possums[5].

Range and habitat

At the time of the arrival of the Europeans in Australia, the thylacine was found only in Tasmania. Its existence on the mainland has been proven by rock art by aboriginal peoples; fossil evidence[6]; footprints found in a cave[7], and a mummy found in western Australia's Nullarbor plain; based on this evidence it had an extensive range on the Australian mainland and New Guinea. Its original habitat was open forest areas and grasslands, but in the last decades of its existence it was pushed by man into dense forests.

Extinction

Thylacine killed in 1869. A strong, yet mistaken, belief that it preyed on domestic sheep led to heavy persecution which ultimately caused the animal's extinction in 1936.

For reasons not fully known thylacines died out New Guinea and the Australian mainland, with the latest fossil finds from the Northern Territory date to 3000 BC. At about 4,000 BC Sulawesi hunters arrived, and with them they brought the dingo[8][9], a canine subspecies of wolf. The theory states that in addition to human hunting, the dingo displaced the thylacine as the top predator through competitive pressure. This thesis is supported by the fact that the thylacine survived on Tasmania into the 20th century, where dingos never appeared[10].

In Tasmania the species was still widespread and frequent at the beginning of the 19th century when European settlers arrived. After the introduction of sheep on the island a bounty was placed by The Van Diemen's Land Company (1830) on the thylacine. In the 1860s the species was confined to the more inaccessible mountainous regions in the south-west of the island, but hunting with traps and dogs continued unabated. Between 1888-1909 the Tasmanian Parliament placed its own bounty of £1, roughly $100 in today's money; it is unknown how many bounties were paid by Van Diemens, but 2,184 hides were collected by the government before its bounty program was halted in 1909. Around the year 1910 the species was regarded as rare. Zoos around the world were looking for these animals.

Although the species were kept in different zoos, just a single litter was made in captivity, at the Melbourne Zoo in 1899[11]. The last known killing of a thylacine in the wild was in 1930. The last known captive specimen - a female named Benjamin - died on the night of 6th to 7th September, 1936 in Hobart's now closed Beaumaris Zoo in Tasmania, apparently from neglect after the keeper shut her out of shelter during harsh weather conditions. Just a few months before, measures were finally taken to protect the species. Several expeditions in the decades that followed did not find any evidence to suggest a survival of the species. In 1966, the Tasmanian government built a protected area of 647,000 hectares in the southwest of the island in the event that some animals were still alive.

Cloning

Sightings of live thylacines have been reported from time to time, but there are no clear photographs or video records; usually, the subject involved may be a dog or fox. Recently, two independent sightings on the Cape York Peninsula in northern Queensland in March 2017 received some news attention[12]. Large rewards are usually offered as well for the capture of a live specimen, such as the March 22, 2005 Australian magazine The Bulletin 750,000 euro reward; these offers always go unclaimed.

In 2007, Australian zoologists from the Australian Center for Ancient DNA at the University of Adelaide wanted to begin DNA analysis of feces collected during the 1950s and 1960s, in the belief that it survived in the wild much longer than previously thought. More ambitious involves outright cloning, which began in 1999 with reconstructing the DNA from preserved tissue samples and a fetus kept in alcohol since 1886[13].

In 2008, researchers from the University of Melbourne and the University of Texas succeeded in introducing the gene Col2A1 enhancer from the thylacine fetus into a transgenic mouse, where it could fulfill the function of the orthologen mouse gene in the mouse's cartilage cells[14][15]. In 2009 another group of samples from two museum expositions sequenced the mitochondrial genome[16][17]. The complete sequencing of the thylacine genome is currently underway at Pennsylvania State University[18]

References

  1. http://www.iucnredlist.org/details/21866/0
  2. "Back from the Dead", Thursday May 30, 2002, Guardian
  3. http://tmag.tas.gov.au/__data/assets/pdf_file/0003/128568/KANUNNAH4.pdf
  4. http://www.australia.gov.au/about-australia/australian-story/tasmanian-tiger
  5. https://www.science.unsw.edu.au/news/thylacines-weak-jaws-linked-its-extinction
  6. http://www.naturalworlds.org/thylacine/palaeontology/prehistoric/prehistoric_range_2.htm
  7. http://www.naturalworlds.org/thylacine/palaeontology/prehistoric/prehistoric_range_3.htm
  8. http://www.sciencemag.org/news/2016/04/how-did-dingo-get-australia
  9. http://www.livescience.com/26246-dingoes-indian-migrants-australia.html
  10. https://www.sciencedaily.com/releases/2007/09/070905095352.htm
  11. Paddle, pg. 231
  12. https://www.theguardian.com/environment/2017/mar/28/tasmanian-tiger-sighting-search-thylacine-queensland-australia
  13. http://www.smh.com.au/news/Science/Clone-again/2005/05/14/1116024405941.html
  14. https://www.ncbi.nlm.nih.gov/pubmed/18493600?dopt=Abstract
  15. http://www.nature.com/news/2008/080520/full/news.2008.841.html
  16. https://www.ncbi.nlm.nih.gov/pubmed/19139089?dopt=Abstract
  17. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2652203/
  18. http://thylacine.psu.edu/
  • Paddle, Robert. The Last Tasmanian Tiger: The History and Extinction of the Thylacine; Cambridge University Press, 2002.

External links