Thylacinus cynocephalus, is variously known as the
Tasmanian tiger, Tasmanian wolf, marsupial wolf, Zebra oppossum, but is not to be confused with the
Tasmanian Devil. It is more precisely known as the thylacine and it is an
extinct marsupial animal which (in the absence of
mammalian competitors in its habitat on the island of
Tasmania) occupied the evolutionary niche normally occupied by the
wolf, that is, the large
predator niche. By
convergent evolution it had come to resemble a wolf or
dog in many respects. It has a rearward opening marsupial pouch, and vertical stripes, hence the "tiger" appellation.
The thylacine was driven extinct (it is believed) by a number of factors. Not the least of which was the bounty offerred by various entities for thylacine carcasses, by for example, the Van Diemen's Land Company, a sheep and cattle raising outfit. Especially vicious, the bounties were progressive, such that, as thylacines became rarer, the bounties increased, to ensure that the effort of tracking and killing them was always worthwhile. Other contributory factors: Habitat destruction, and a distemper-like disease epidemic around 1910. A farmer named Will Batty made the last known thylacine sighting in the wild in 1936 when he shot and killed one. The Tasmanian government declared the thylacine a protected species in 1936 just two months before the last individual in captivity died.
You can find out more about the thylacine in David Quammen's excellent book, The Song of the Dodo, ISBN 0-684-80038-7, or Eric Guiler's Thylacine: The Tragedy of the Tasmanian Tiger.