The echidna and the platypus are non-placental mammals. They are monotremes, or egg-laying mammals. Kangaroos, wallabies, koalas, bandicoots, wombats and Tasmanian devils are just a few other...
There are many marine mammals, all of which are placental, including dolphins, and the dugong, or sea-cow. The only placental mammals native to Australia are bats, of which there are over 80 species,...
There are no placental mammals which lay eggs. The only two egg-laying mammals in existence are the platypus and the echidna, which are classed as monotremes. They are still classified as mammals...