The Red Kangaroo and Emu that support the shield are the unofficial animal emblems of the nation. They owe this recognition to the fact that they are native Australian fauna, (found only on that continent), and were more than likley chosen because they are the only native Australian animals that are large enough to hold up a shield. It is however often atributed to the mistaken belief that neither animal can move backward, only forward - ie. progress (the reality being that both animals can, but infrequently do).

They both have the muscles required to step backwards. It's kind of like getting a cow to walk down stairs. They can do it, but would really rather not. Getting them upstairs is fairly easy.