Cassowaries are flightless birds of the genus Casuarius, in the order Casuariiformes. They are classified as ratites, flightless birds without a keel on their sternum bones. Cassowaries are native to the tropical forests of New Guinea, the Moluccas, and northeastern Australia. Three cassowary species are extant.

Fossil evidence indicates clearly that marsupials originated in the New World. The oldest known marsupial fossils (which have been found in both China and North America) date from approximately 125 million years ago, during the Cretaceous Period (145 to 66 million years ago). Their presence in Australia and nearby islands is thought to have occurred from a single migration event in which a group of ancestral marsupials colonized Australia by using land connections with South America via Antarctica.