Aboriginal rock art recording 15,000 years of life in the Arnhem Land region of Australia has been discovered by a team of scientists, the Independent reports. At least 100 sites are spread out over the Wellington mountain range, and the diverse imagery ranges from thylacines, an ancient mammal, to modern-day cars, biplanes, and rifles.

The paintings, which include 81 recorded images of ships, undermine the long held assumption that the Australian continent was isolated and mostly unvisited until 1778, when the First Fleet arrived.

Scientists surveying the paintings say that 20th-century rock art is extremely rare, and that the works at Wellington may be the longest continuous record of human habitation in the world. "This seems to have been a key location where people went back again and again, adding to the art over thousands of years and many hundreds of generations," said Professor Paul Tacon, an archaeologist from Griffith University in Queensland.

"Each time they went back, they added new imagery and new experiences to the growing history book that they were creating," he added. "Many Aboriginal people across northern Australia describe these sorts of sites as their history books, or libraries."

The rock art at Wellington was discovered in the 1970s, when an expert, George Chaloupka, was led to the site by local people. But he only saw a small area of it, and records of its location were lost. The site was recently rediscovered by Daryl Guse, a doctoral student working with an Aboriginal elder, Ronald Lamilami.

Emphasizing the importance of the site, Professor Tacon said: "This area is of World Heritage significance, and it rivals the best of any area in Australia. It's right up there with the best rock art regions of Europe and South Africa and elsewhere."