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UNTIL now, the egg-laying monotremes were only known from the Australian continent, where they have lived since the early Cretaceous period to the present¹. Here we report the first monotreme from outside the Australian continent, an ornithorhyn-chid, from sediments of late early Palaeocene age in Patagonia, southern Argentina. This discovery demonstrates the Gondwanan nature of monotremes and supports the hypothesis that the Patagonian Terrane of southern South America had a biotic history distinct from that of the rest of the continent.