Giant prehistoric kangaroos died out when "climate cataclysms" turned Australia's lush tropical forest into a desert, scientists said after studying ancient fossils using new techniques.

Weighing up to 170 kilograms — almost twice as much as the largest living kangaroos — the extinct species Protemnodon hopped around Australia around five million years ago.

Researchers were able to reconstruct the feeding habits of one population by comparing long-lasting chemicals from fossilized teeth with recently discovered rocks.

Similarities in chemical composition helped determine how far the kangaroos hopped in search of food.

Scientists found that the mega-herbivores lived in what was then a lush tropical forest, rarely straying far from home in search of food.

The rainforest began to dry out around 300,000 years ago, when the climate in the region became "increasingly dry and unstable."

"The giant kangaroos' desire to stay close to home during the major climate changes 300,000 years ago probably contributed to their extinction," the researchers say.

Giant kangaroo species survived in other parts of Australia and Papua New Guinea, with the last populations living until about 40,000 years ago. | BGNES, AFP