Forty to fifty million years ago, when the climate of the Antarctic was mild and seasonal, some of the largest birds ever known flew and hunted over its waters. They’re known as Bony-toothed Birds. Fossils show that most had wingspans of more than 12 feet. Their beaks were evenly studded tooth-like outgrowths up to an inch long. They likely skimmed fish and squid off of the water’s surface. Learn more at BirdNote.org.