Marsupial mammals dispersed from South America to Australia by way of an Antarctic land bridge, which no longer exists.Placental mammals arose later and subsequently spread to other continents, typically outcompeting marsupials wherever they coexisted.Today, Australia has about half marsupials and half placental mammals, mostly bats and rodents.This abundance of marsupials in Australia and their rarity elsewhere is likely due to a lack of

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The abundance of marsupials in Australia and their rarity elsewhere is primarily due to a lack of dispersal opportunities for marsupials to other continents, as placental mammals often outcompeted them where they coexisted.

Marsupial Mammals Dispersed from South America to Australia by Way