We report a new species of shearwater, Ardenna buchananbrowni sp. nov., from the Pliocene of New Zealand. It is both the smallest and oldest known diving member of the genus, demonstrating that this now abundant form of shearwater has had a long presence in southern oceans. Ardenna buchananbrowni sp. nov. is among the few extinct shearwaters described from the Southern Hemisphere and adds to an ...