Phoenicopteriformes is a group of water birds which comprises flamingos and their extinct relatives.
Flamingos and their relatives are well attested in the fossil record, with the first unequivocal member of the Phoenicopteridae, Elornis known from the late Eocene epoch. An extinct family of peculiar "swimming flamingos", the Palaelodidae, are believed to be the closest relatives of the modern flamingos, with the extinct genus Juncitarsus slightly more primitive than the group which contains flamingos and grebes (Mirandornithes). The foot and wing anatomy of the palaelodids suggests that they were surface-swimming birds, rather than grebe-like divers as was proposed in the past. Whether swimmers or divers, that both primitive phoenicopteriforms and their closest relatives, the grebes, were highly aquatic, indicates that the entire clade Mirandornithes evolved from aquatic, probably swimming ancestors.