Like today’s swans, the extinct species Annakacygna hajimei and Annakacygna yoshiiensis were quite large. But unlike their modern relatives, these birds lived most of their lives out at sea, and their fossils reveal remarkable adaptations to this unusual lifestyle. This led the researchers who first described these species to dub them “the ‘ultimate bird’ that ever existed.”More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.