極地鳥屬

極地鳥屬; 化石時期：白堊紀晚期（英語：Late Cretaceous）66 Ma PreЄ Є O S D C P T J K Pg N ▼
科學分類
界：	動物界 Animalia
門：	脊索動物門 Chordata
綱：	鳥綱 Aves
演化支：	雁形類 Anserimorphae
目：	†維加鳥目 Vegaviiformes
科：	†維加鳥科 Vegaviidae; Chatterjee（英語：Sankar Chatterjee） 2002
屬：	†極地鳥屬 Polarornis; Chatterjee 2002
模式種
	傑氏極地鳥; Polarornis gregorii; Chatterjee 2002

極地鳥屬（學名：Polarornis）是雁形類（Anserimorphae）已滅絕的一個屬，屬維加鳥科，僅有Polarornis gregorii一種，其化石出土於南極洲西摩島Lopez de Bertodano組（英語：Lopez de Bertodano Formation），年代為距今約6600萬年白堊紀晚期（英語：Late Cretaceous）的馬斯垂克期。極地鳥最早於1988年由古生物學家桑卡爾·柯特吉（英語：Sankar Chatterjee）發現^[1]，但直到2002年才正式描述發表^[2]，不過他在1997年便在其著作The Rise of Birds中使用了本屬的學名^[3]。

分類

柯特吉將極地鳥屬歸入潛鳥科，認為其為潛鳥較早分支的類群，許多學者認同此觀點^[4]^[5]，但也有人反對，例如傑拉爾德·梅爾（英語：Gerald Mayr）即認為極地鳥的解剖特徵和其他潛鳥差異過大^[6]^[7] 。2017年一篇研究將極地鳥與同出土於南極的白堊紀鳥類維加鳥屬、智利出土的白堊紀鳥類Neogaeornis（英語：Neogaeornis）、新西蘭出土的古新世鳥類南鳥屬（Australornis）一起歸入新科維加鳥科，為雁形類較早分支的演化支^[8]。

習性

極地鳥應為以魚類與無脊椎動物為食的水鳥，其生態棲位可能與潛鴨和黃昏鳥相似。有研究顯示極地鳥的股骨中心密實，不同於多數鳥類中空的股骨，顯示極地鳥應不具（或接近不具）飛行能力，與企鵝和黃昏鳥相仿^[9]。

參考文獻

^ Chatterjee, S. The oldest Antarctic bird. Journal of Vertebrate Paleontology. 1989, 8 (3): 11A.
^ Chatterjee, S. (2002). "The morphology and systematics of Polarornis, a Cretaceous loon (Aves: Gaviidae) from Antarctica." Pp. 125-155 in Zhou and Zhang (eds), Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution, Beijing, 1–4 June 2000. Beijing: Science Press.
^ Chatterjee, S. (1997). The Rise of Birds. Baltimore: Johns Hopkins University Press.
^ Olson, S. Neogaeornis wetzeli Lambrecht, a Cretaceous loon from Chile (Aves, Gaviidae). Journal of Vertebrate Paleontology. 1992, 12 (1): 122–124. doi:10.1080/02724634.1992.10011438.
^ Hope, S. (2002). "The Mesozoic radiation of Neornithes." Pp. 339-388 in Chiappe, L.M. and Witmer, L. (eds.), Mesozoic Birds: Above the Heads of Dinosaurs
^ Mayr, G. A partial skeleton of a new fossil loon (Aves, Gaviiformes) from the early Oligocene of Germany with preserved stomach content (PDF). Journal of Ornithology. 2004, 145 (4): 281–286 [2006-11-07]. doi:10.1007/s10336-004-0050-9. （原始內容 (PDF)存檔於2015-09-24）.
^ Feduccia, A. (1999). The Origin and Evolution of Birds. 2nd edition. Yale University Press.
^ Agnolín, F.L.; Egli, F.B.; Chatterjee, S.; Marsà, J.A.G. Vegaviidae, a new clade of southern diving birds that survived the K/T boundary. The Science of Nature. 2017, 104 (87): 87. PMID 28988276. doi:10.1007/s00114-017-1508-y.
^ Chinsamy, A.; Martin, L.D.; Dobson, P. Bone microstructure of the diving Hesperornis and the volant Ichthyornis from the Niobrara Chalk of western Kansas. Cretaceous Research. 1998, 19 (2): 225–235. doi:10.1006/cres.1997.0102.

[chatterjee1989-1] Chatterjee, S. The oldest Antarctic bird. Journal of Vertebrate Paleontology. 1989, 8 (3): 11A.

[chatterjee2002-2] Chatterjee, S. (2002). "The morphology and systematics of Polarornis, a Cretaceous loon (Aves: Gaviidae) from Antarctica." Pp. 125-155 in Zhou and Zhang (eds), Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution, Beijing, 1–4 June 2000. Beijing: Science Press.

[chatterjee1997-3] Chatterjee, S. (1997). The Rise of Birds. Baltimore: Johns Hopkins University Press.

[olson1992-4] Olson, S. Neogaeornis wetzeli Lambrecht, a Cretaceous loon from Chile (Aves, Gaviidae). Journal of Vertebrate Paleontology. 1992, 12 (1): 122–124. doi:10.1080/02724634.1992.10011438.

[hope2002-5] Hope, S. (2002). "The Mesozoic radiation of Neornithes." Pp. 339-388 in Chiappe, L.M. and Witmer, L. (eds.), Mesozoic Birds: Above the Heads of Dinosaurs

[mayr2004-6] Mayr, G. A partial skeleton of a new fossil loon (Aves, Gaviiformes) from the early Oligocene of Germany with preserved stomach content (PDF). Journal of Ornithology. 2004, 145 (4): 281–286 [2006-11-07]. doi:10.1007/s10336-004-0050-9. （原始內容 (PDF)存檔於2015-09-24）.

[feduccia1999-7] Feduccia, A. (1999). The Origin and Evolution of Birds. 2nd edition. Yale University Press.

[agnolínetal2017-8] Agnolín, F.L.; Egli, F.B.; Chatterjee, S.; Marsà, J.A.G. Vegaviidae, a new clade of southern diving birds that survived the K/T boundary. The Science of Nature. 2017, 104 (87): 87. PMID 28988276. doi:10.1007/s00114-017-1508-y.

[Chinsamy-9] Chinsamy, A.; Martin, L.D.; Dobson, P. Bone microstructure of the diving Hesperornis and the volant Ichthyornis from the Niobrara Chalk of western Kansas. Cretaceous Research. 1998, 19 (2): 225–235. doi:10.1006/cres.1997.0102.

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