Kangaroos are marsupials, that unique group of mammals that originated in the Americas, then crossed Antarctica 55 million years ago to end up in Australia by around 25 million years ago. Although kangaroos do not belong to a single species, but to several related species in the family Macropodidae, the group is characterized in the mind of the public as all having disproportionately large hind legs and a propensity to hop along the savannas that it inhabits.
But people today would probably not even recognize the ancestors of these iconic mammals, which were opossum-like critters that spent their lives up in the trees and first ate fruits and then tree leaves. The prevailing view at one time was that the kangaroos did not move down from the trees until around 15-5 million years ago, when growing aridity in Australia caused them to gradually evolve to have the attributes we see in them today.
|Modern kangaroos loiter about in their grassland home (by By AWS10)
|Modern Tree Marsupial, who remained in the trees, by By Fred Hsu