Despite the varied range of forms, there is a common body plan to all members of this group. They are often referred to as the 'macropods' from the scientific name of the superfamily, which translates from the Greek to mean 'big -footed'. This term describes one of their most defining and distinctive characteristics; long toes on big feet, on the end of strong hindlegs. This physical feature allows, especially in the larger species, for a fast and efficient hopping gait. In contrast, the arms and hands are generally much shorter and weaker.

Eastern Grey Kangaroos, Blue Mountains

Historically, there have been many different families of kangaroos. Some of these contained members that were probably carnivorous in habit. All living macropods, however, are essentially herbivorous, the smaller ones being a little more omnivorous, and the larger ones being more standard grazers. All of the extant species belong to two families; the smaller, more primitive potoroids ('rat kangaroos', 'potoroos', 'bettongs'), and the generally larger and more recently evolved macropodids (kangaroos and various wallabies).

All species have a well-developed pouch that opens forwards, and with muscles at the top that can lock the young in or out. And even though the pouch covers four teats, all but one species give birth one at a time, one after another, for their entire life. This often results in the mother kangaroo having three offspring at any one time, all at different stages; an embryo inside, a joey in the pouch, and a young by the side. This is when the multiple teats are used; the different teats actually produce different types of milk for the differently aged young. Another interesting feature of this reproductive cycle is the condition known as 'embryonic diapause', found in the macropodoids and a few other types of mammals. The female kangaroo can mate and fertilize immediately after birth, but can then put 'on hold' the development of the embryo, dependent on the progress of the current pouched young. This allows for the quick replacement of young, for the 'frozen' embryo will resume development if the pouched young dies.

a kangaroo joey opening mother's pouch