Why are most marsupials found in Australia?
Most marsupials are found in Australia because the continent separated from the other landmasses of Gondwana tens of millions of years ago. In isolation, marsupials diversified to fill many ecological roles that placental mammals fill elsewhere.
Marsupials are mammals that give birth to tiny, undeveloped young, which usually continue developing in a pouch. Kangaroos, koalas, wombats and possums are examples.
Fossils show that marsupials once lived in South America, Antarctica and Australia when they were joined as part of Gondwana. Australia then broke away and drifted north.
Adaptive radiation
With few competing placental mammals, Australian marsupials evolved into many forms, from tiny carnivorous dunnarts to large grazing kangaroos. Some resemble placental animals elsewhere, such as the sugar glider and the flying squirrel.
Today, Australia and nearby New Guinea are home to more than 200 marsupial species. Others live in the Americas, including opossums.
Australia's marsupials face threats from introduced predators such as foxes and cats. Many species have become extinct since European settlement.
Conservation programs, predator-free sanctuaries and fenced reserves now help protect threatened species such as the bilby and the numbat.