ainult Austraalias ja selle lähedastel saartel elavate ürgimetajate selts, sellesse kuuluvad nokkloomlased ja sipelgasiillased, order of egg-laying mammals, which includes the amphibious platypus (family Ornithorhynchidae) and the terrestrial echidnas (family Tachyglossidae) of continental Australia, the Australian island state of Tasmania, and the island of New Guinea