The Megaceryle large green kingfishers were formerly placed in Ceryle with the Pied Kingfisher, but the latter is closer to the Chloroceryle American green kingfishers.
Not longer than 5 million years ago - possibly as recently as 2.9 million years ago -, an Old World giant kingfisher became the ancestor of the Belted and Ringed Kingfishers, and later, another species related to the Pied Kingfisher became the ancestor of the Chloroceryle green kingfishers after colonizing the Americas.