The systematic position of the Eocene bird Asiavis phosphatica
A.V. Panteleyev
Abstract. Asiavis phosphatica from the Uppermost Middle Eocene of Uzbekistan is redescribed and placed in the Anseriformes (subfamily Cygninae). Originally this bird was placed in Gruiformes (family incertae). A. phosphatica is the oldest known cygnine.
Zoosystematica Rossica, 1999, 8(2): 351–352 ▪ Published in print 16 March 2000
Open full article 
References
Averianov, A.O., Panteleyev, A.V., Potapova, O.R. & Nessov L.A. 1991. Bony-toothed birds (Aves: Pelecaniformes: Odontopterygia) of the Late Paleocene and Eocene of the western margin of ancient Asia. Trudy zool. Inst. Akad. Nauk SSSR, 239: 3-12. (In Russian with English summary.)
Howard, H. 1992. New record of Middle Miocene anseriform birds from Kern County, California. Nat. Hist. Mus. Los Angeles County, Sci. Ser., 36: 231-237.
Kurochkin, E.N. 1985. Ptitsy Tsentral'noi Azii v pliotsene [Birds of Central Asia in Pliocene]. 128 p. Moscow. (In Russian with English summary.)
Lambrecht, K. 1931. Gallornis straeleni n. g., n. sp., ein Kreidevogel aus Frankreich. Bull. Mus. r. Hist. nat. Belg., 7(31): 1-6.
Miller, L. 1925. Cheudytes, a diving goose from the California Pleistocene. The Condor, 27: 145-147. https://doi.org/10.2307/1362992
Nessov, L.A. 1986. The first finding of Late Cretaceous bird Ichthyornis in the Old World and some other bird bones from Cretaceous and Paleogene of Soviet Middle Asia. Trudy zool. Inst. Akad. Nauk SSSR, 147: 31-38. (In Russian with English summary.)
Nessov, L.A. 1992a. Mesozoic and Paleogene birds of the USSR and their paleoenvironments. Nat. Hist. Mus. Los Angeles County, Sci. Ser., 36: 465-478.
Nessov, L.A. 1992b. Review of localities and remains of Mesozoic and Paleogene birds of the USSR and the description of new findings. Russ. J. Ornitol., 1(1): 7-50. (In Russian with English summary.)