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Scientists in Australia have discovered the country's oldest known rock art, and it's a drawing of a kangaroo!

The kangaroo painting is around two metres long, and is made from red ochre paint, which is used in many ancient rock paintings.

It was found by researchers in Western Australia's Kimberley region, which is known for its ancient Aboriginal rock paintings.

The researchers used a technique called radiocarbon dating to try to find out how old the painting was and discovered it was around 17,300 years old.

Finding out how old rock art is, is really hard.

This is because aboriginal artists used a paint made from iron oxide pigments (or ochre), which has no organic material in it, like plants, and that means that radiocarbon dating can't be used.

However, a scientist from the University of Melbourne, named Dr David Finch, invented a technique that meant that scientists could make a pretty accurate estimation of how old rock art paintings are.

And the answer lies with ancient mud-wasps!

Mud-wasps built their nests in the rocky caves around the painting, and because the nests are made from organic material, like mud and charcoal, scientists can use them to help give an estimate to how old the painting is.

To find out how old the kangaroo painting was Dr Finch said: "We radiocarbon dated three wasp nests underlying the painting and three nests built over it to determine, confidently, that the painting is between 17,500 and 17,100 years old; most likely 17,300 years old".

The kangaroo art might be the oldest in Australia, but a drawing found in South Africa is thought to be the oldest known drawing in the world, at 73,000 years old.