Or simply an artist's active imagination. What's your basis for drawing the conclusion that it is more likely that the drawing was from direct observation of a living animal, and not from an artist's rendering of an animal from observed fossils or that it was an invention of the artist's imagination?
What evidence leads you to believe that one possibility is reasonable, and the other two not?
Extinct Thylacine petroglyph depicted at Murujuga, Dampier, West Australia.
These creatures became extinct on the Australian mainland thousands of years before European settlement of the continent, but survived on the island of Tasmania.
They likely preferred the dry eucalyptus forests, wetlands, and grasslands in continental Australia. Indigenous Australian rock paintings indicate that these animals lived throughout mainland Australia and New Guinea. Proof of their existence in mainland Australia came from a desiccated carcass that was discovered in a cave in the Nullarbor Plain in Western Australia in 1990. Carbon dating revealed its remains to be about 3,300 years old.
Aboriginal cave painting of a Thylacine and its cub in the Pilbara region of West Australia dating back 6,000 years.
Fossils don't have stripes. What is it that you find so threatening in the theory that pre-historic people depicted the creatures THEY SAW!