The Tasmanian tiger — also known as the Thylacine or, formally, Thylacinus cynocephalus — was a small, doglike, marsupial mammal. According to The I-Spyder Book of Earth Creatures, it had "a smooth brown coat with black or darker brown stripes on its rear." Its tail made up over third of its 160 centimetre length. As with many mammals, males were generally larger than females.
It became extinct due to targeted killing by humans in the 20th century. Natural disease was also a contributing factor to their extinction, which finally occurred in 1936. The last — or, according to Martha Jones, the penultimate — Tasmanian tiger died in captivity at the Beaumaris Zoo. The real last Thylacine was an exhibit at the Museum of the Last Ones.