The marsupial lion was Australia's largest carnivorous mammal.

Their remains have only recently been unearthed and are throwing new light on the so-called megafauna that lived in the region many thousands and even millions of years ago and more.

An exhibition - Australia's Lost Kingdoms - presents life-sized representations of some of the creatures. It includes a turtle as big as a small car and a carnivorous duck equipped with a bill the size and shape of an axe.

Professor Mike Archer, director at the Australian Museum, says new scientific discoveries show Australia was once a land of giants.

"Contrary to what the Americans have tried to tell us - that the biggest of everything comes from Texas - in the way of dinosaurs the biggest things were actually in Australia. We had monsters that made the rest of the world's dinosaurs look like geckos!"

Meat cleavers

One of those monsters was a seven-metre long goanna lizard (Megalania prisca). An adult would have weighed up to 600 kg. Then there were the tree-climbing crocodiles, (Trilophosuchus rackhami) nicknamed the "drop crocs" for the way they are thought to have leapt down on to their victims.

"And if that didn't get you," Professor Archer said, "there were meat-eating kangaroos that would have stood up at your shoulder and torn your arm off.

Fulgurotherium roamed Australia 110 million years ago

This kangaroo had a taste for flesh.

"As the climate started to dry and cool, particularly, animals tended to get larger. And a lot of the megafauna culminated in the cool, if not icy conditions of the Pleistocene (1.8 million to 11,000 years ago). And Australia was no exception.

Scientists have based their new interpretation on fossils found in sites like the one at Riversleigh in outback Queensland. Palaeontologist Phil Creaser says animal remains have been preserved better there than almost anywhere else in the world.

"The waters that they either fell in or were moved by were very rich in calcium carbonate. This is the limestone rock that we see today.

"What we assume has happened is that these fossils, or the animals once they've fallen in these waters and pools, quickly had a coat of this calcium carbonate, the limestone around them. They became entombed, which means that you've got nearly perfect preservation.

"There's been no movement of the fossils. There've been no scavengers to chew them up."

Human habitation

Perhaps most intriguing of all is the knowledge that many of these animals, including the marsupial lion, existed at the same time as the earliest Aboriginal inhabitants of Australia, who are thought to have come to the continent around 50,000 years ago.

"In fact all of the animals that you see in the exhibition - the huge horned turtle, the marsupial lion and the large kangaroo overlapped with humans," Dr Musser says.

The large kangaroo has been found at a site called Cuddie Springs in conjunction with human habitation."

Today, Australia is losing species at a rate not seen since the extinction of the dinosaurs. The museum hopes that its exhibition, which runs until next April, will help people better understand the past - and learn to conserve the present.

Australia's Lost Kingdoms will visit the UK in 2002.