It stood tall at 6’5, weighed over 500lbs, had the face of a koala and the body of a sturdy kangaroo. And apparently it was delicious.

Scientists think they have discovered the reason behind the demise of the prehistoric Australian marsupial Procoptodon goliah – better known as the giant, short-snouted kangaroo. They say it was not climate change, as has always been assumed, but hungry Ice Age hunters.

The animal – about three times bigger than a modern-day kangaroo and with slightly different features - was one of many Ice-Age megafauna whose demise has long been debated among experts, but usually put down to the changing environment.

However an international team of scientists, led by Gavin Prideaux from Flinders University in South Australia, has discovered a different theory behind the reason the animal became extinct 45,000 years ago.

The research, published this week in the US journal Proceedings of the National Academy of Sciences , not only shines a new light on the demise of the animal – the largest kangaroo ever to evolve - but also on the landscape of Australia at the time.

While the scientists were unable to uncover direct proof of the hunting theory – such as a fossil or the like displaying wounds – they did so by a process of elimination.

The team studied the anatomy of the giant kangaroo’s skull as well as scratches on its teeth and isotopes in the tooth enamel, and determined that it had a “strong preference” for drought-tolerant plants such as saltbushes, rather than grass which is the staple diet of the modern-day kangaroo.

It had also evolved in response to arid conditions, but became extinct during one of the wetter periods it had previously survived – 5,000 years after humans are thought to have first arrived in Australia.

The high intake of saltbushes would have meant the giant kangaroo drank more water and would have been frequently found at waterholes and therefore vulnerable to hunters.

These combined factors led the scientific team to determine that “human hunting was a more likely extinction cause”.

“If Procoptodon goliah ate a lot of saltbush, then just like modern saltbush-fed sheep, it probably needed to drink more regularly than its grazing contemporaries,” Dr Linda Ayliffe, a US-based member of the scientific team, said.

And, just like saltbush-fed sheep, it would have tasted good too, according to Dr Prideaux, an Australian palaeontologist who specialises in the giant kangaroo.

Describing the animal, which was thought to have been in abundance across the whole of Australia, Dr Prideaux said it had “the head of a koala – minus the fluffy ears – and the body of a giant, solid kangaroo”.

Unlike its modern-day relatives, the giant kangaroo was very big and imposing and not as agile.

“These were a lot slower and gravitated towards waterholes, so they were basically sitting ducks for the humans,” Dr Prideaux told The Times.

“And they fed on saltbush so if you think the modern kangaroo tastes nice, this would have been lovely.”

According to the scientists, Australia was also once the home to rhinoceros-sized herbivores, marsupial lions, giant wombats and giant lizards, and suffered the worst extinctions of all the continents, losing 90 per cent of the larger species by 40,000 years ago.

Despite the extinction of the Procoptodon goliah, kangaroos are now commonly found in Australia. Along with the emu, the iconic Australian marsupial is featured on the country’s national coat of arms.

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