Macropods are marsupials belonging to the family Macropodidae, which includes kangaroos, wallabies, tree-kangaroos, pademelons, and several others. Before European settlement, there were about 53 species of Macropods. Six species have since become extinct. Another 11 species have been greatly reduced in numbers.
In common use the term kangaroo is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo.
A wallaby is any of about thirty species of macropod (Family Macropodidae). It is an informal designation generally used for any macropod that is smaller than a kangaroo or wallaroo that has not been given some other name.
A wallaroo is any of three closely related species of moderately large macropod, intermediate in size between the kangaroos and the wallabies, the name "wallaroo" is a portmanteau of wallaby and kangaroo. The earliest known fossil macropod dates back about 11.61mya to 28.4mya, either in the Miocene or Late Oligocene, and was uncovered in South Australia. Unfortunately, the fossil could not be identified any further than the family. A Queensland fossil of a species similar to Hadronomas has been dated at around 5.33mya to 11.61mya, falling in the Late Miocene or Early Pliocene. The earliest completely identifiable fossils are from around 5.33mya. Procoptodon goliah, the largest kangaroo that ever existed, stood approximately 3 metres (10 feet) tall and weighed about 230 kilograms, the genus was present until at least about 50,000 years ago before going extinct.