thylacines were common across australia. fossil remains have been found in queensland, paintings have been found in western australia, and a mummified body was found in cave on the nullabor plain in south australia. the body was dated as being 4,650 years old. the thylacine began to disappear from the australian mainland about 5,000 years ago. this is about the same time as the arrival in australia of the dingo. because of rising sea levels 10,000 years ago, tasmania was separated from the australian mainland by bass strait which the dingo never crossed. by the time europeans came to australia in 1788, the thylacine was only living in tasmania.