古巨蜥

古巨蜥; 化石時期：1.5–0.04 Ma PreЄ Є O S D C P T J K Pg N ▼ 更新世
科學分類
界：	動物界 Animalia
門：	脊索動物門 Chordata
綱：	爬蟲綱 Reptilia
目：	有鱗目 Squamata
科：	巨蜥科 Varanidae
屬：	巨蜥屬 Varanus
種：	古巨蜥 V. priscus
二名法
	Varanus priscus; (Owen, 1859)
異名
	原用名 Megalania prisca Owen, 1859（互用名）; ; 主觀異名 Notiosaurus dentatus Owen, 1884; Varanus dirus de Vis, 1889; Varanus warburtonensis Zeitz, 1899; ;

古巨蜥（學名：Varanus priscus）又名巨齒蜥，是一種已滅絕的巨型巨蜥。牠們生存於更新世的南澳洲，約於4萬年前消失。最早到達的澳洲原住民可能曾與之一同生活。^[3]

科學分類

四種巨蜥的體型比較（3A與3B者）。

分類及命名

古巨蜥是由理查·歐文（Richard Owen）所描述，並取命名為Megalania prisca，意為「古代巨型的流浪者」。^[1] 歐文最初將古巨蜥分類在自己的屬中，但此屬的有效性卻被受質疑，認為是巨蜥屬的異名。^[4] 由於Megalania及巨蜥屬的性別不同，種小名也由prisca改為priscus。^[5]

系統發生學

多項研究都嘗試找出古巨蜥在巨蜥屬內的系統發生學位置。其中一個指牠們的頭顱骨頂形態與眼斑巨蜥相似，認為與之相近。^[6] 另一項較近期的研究則指牠們與科莫多龍的腦顱結構相似，故與之應為姊妹分類，而樹巨蜥則為其最近親。^[7]

體型

古巨蜥的骨骼結構重構。

古巨蜥的頭顱骨。

古巨蜥沒有留下完整或接近完整的骨骼，故很難確定其大小。^[4] 早期估計牠們最大約有7米長，及重600-620公斤。^[8] 於2002年，史蒂芬·羅（Stephen Wroe）就認為古巨蜥最多只有4.5米長及重331公斤^[9]，而平均則長3.5米及重97-158公斤。^[9]^[10] 他認為早期的計算是基於錯誤的方法及誇大了其體型。^[9]

不過，Ralph Molnar於2004年基於脊骨及總體長的研究，指古巨蜥的體長有幾種可能性。^[4] 若古巨蜥像樹巨蜥般擁有幼長的尾巴，牠們有可能長達7.9米；若牠們的尾巴與體型的比例像近親科莫多龍，則體長約等於7米。以7米的體長來計算，牠們可以重達1940公斤．而平均重320公斤。^[4]

古生物學

古巨蜥是已知最巨型的陸上蜥蜴(海中最大的蜥蜴則是滄龍)，牠們的四肢及身體強壯，頭顱骨很大，眼睛間有細小的冠，顎骨上長滿鋸齒狀的牙齒。^[5] 從其體型來推斷，牠們主要獵食中型至大型的動物，包括任何巨型的有袋類（如雙門齒獸）、爬行類、細小的哺乳動物及鳥類。

史蒂芬·羅等人懷疑古巨蜥是否澳洲巨型動物群的主要掠食者。^[11] 他們發現袋獅曾殘殺非常巨型的更新世哺乳動物，但古巨蜥卻沒有。他們也發現古巨蜥的化石並不普遍，與袋獅的分佈相形見絀。

提姆·富蘭納瑞（Tim Flannery）認為要重構澳洲原住民到達澳洲前的生態系統，最理想的方法是以科莫多龍來取代古巨蜥。^[12]

毒素

研究發現其他巨蜥屬的成員，如科莫多龍，沿顎部都有毒腺。^[13] 所以有指古巨蜥也可能有類似的毒腺。^[14] 若真是這樣，古巨蜥將會是最巨大的有毒脊椎動物。

參考文獻

^ ^1.0 ^1.1 Owen R. Description of Some Remains of a Gigantic Land-Lizard (Megalania Prisca, Owen) from Australia. Philosophical Transactions of the Royal Society of London. 1859, 149: 43–48. JSTOR 108688. doi:10.1098/rstl.1859.0002.
^ Lydekker R. Catalog of the fossil Reptilia in the British Museum (Natural History) Cromwell Road S.W. Pt. 1: The Orders Ornithosauria, Crocodilia, Squamata, Rhynchocephalia, and Proterosauria. London: The Trustees. 1888. Cited in Molnar RE. The long and honorable history of monitors and their kin. King, Ruth Allen; Pianka, Eric R.; King, Dennis (編). Varanoid lizards of the world. Bloomington: Indiana University Press. 2004: 45. ISBN 0-253-34366-6. )
^ Megalania, giant ripper lizard Archive.is的存檔，存檔日期2012-05-26, BBC - Science & Nature
^ ^4.0 ^4.1 ^4.2 ^4.3 Molnar, R.E. Dragons in the Dust: The paleobiology of the giant monitor lizard Megalania. Indiana University Press. 2004.
^ ^5.0 ^5.1 Molnar, R.E. History of monitors and their kin. Pianka, E.R., King, D. and King, R.A. (Editors) (編). Varanoid lizards of the world. Indiana University Press. 2004: 588 pp.
^ Lee MSY. Possible affinities between Varanus giganteus and Megalania prisca. Memoirs of the Queensland Museum. 1996, 39: 232.
^ Head, JJ.; Barrett, PM.; Rayfield, EJ. Neurocranial osteology and systematic relationships of Varanus (Megalania) prisca Owen, 1859 (Squamata: Varanidae). Zoological Journal of the Linnean Society. 2009, 2009 (155): 445–57.
^ Hecht, M. The morphology and relationships of the largest known terrestrial lizard, Megalania prisca Owen, from the Pleistocene of Australia. Proceedings of the Royal Society of Victoria. 1975, 87: 239–50.
^ ^9.0 ^9.1 ^9.2 Wroe, S. A review of terrestrial mammalian and reptilian carnivore ecology in Australian fossil faunas, and factors influencing their diversity: the myth of reptilian domination and its broader ramifications (PDF). Australian Journal of Zoology. 2002, 50: 1–24 [2009-09-28]. （原始內容 (PDF)存檔於2003-12-10）.
^ Wroe S, Field J, Fullagar R, & Jermiin LS. Megafaunal extinction in the late Quaternary and the global overkill hypothesis. Alcheringa. 2004, 28: 291–331.
^ Wroe S, Myers TJ, Wells RT & Gillespie, A. Estimating the weight of the Pleistocene marsupial lion, Thylacoleo carnifex (Thylacoleonidae : Marsupialia): implications for the ecomorphology of a marsupial super-predator and hypotheses of impoverishment of Australian marsupial carnivore faunas. Australian Journal of Zoology. 1999, 47: 489–98.
^ Flannery T. The Future Eaters. 1994: pp. 384–5. ISBN 0-8021-3943-4.
^ Fry, B.; et al. Early evolution of the venom system in lizards and snakes. Nature. February 2006, 439: 584–8 [2009-09-28]. doi:10.1038/nature04328. （原始內容存檔於2009-04-19）.
^ Komodo Dragons Kill With Venom, Researchers Find （頁面存檔備份，存於網際網路檔案館） (National Geographic)

外部連結

Prehistoric Life - Museum Victoria
The UnMuseum （頁面存檔備份，存於網際網路檔案館）

[Owen1859-1] 1.0 ^1.1 Owen R. Description of Some Remains of a Gigantic Land-Lizard (Megalania Prisca, Owen) from Australia. Philosophical Transactions of the Royal Society of London. 1859, 149: 43–48. JSTOR 108688. doi:10.1098/rstl.1859.0002.

[Lydekker1888-2] Lydekker R. Catalog of the fossil Reptilia in the British Museum (Natural History) Cromwell Road S.W. Pt. 1: The Orders Ornithosauria, Crocodilia, Squamata, Rhynchocephalia, and Proterosauria. London: The Trustees. 1888. Cited in Molnar RE. The long and honorable history of monitors and their kin. King, Ruth Allen; Pianka, Eric R.; King, Dennis (編). Varanoid lizards of the world. Bloomington: Indiana University Press. 2004: 45. ISBN 0-253-34366-6. )

[3] Megalania, giant ripper lizard Archive.is的存檔，存檔日期2012-05-26, BBC - Science & Nature

[Molnar,_2004-4] 4.0 ^4.1 ^4.2 ^4.3 Molnar, R.E. Dragons in the Dust: The paleobiology of the giant monitor lizard Megalania. Indiana University Press. 2004.

[Molnar,_2004;_in_Pianka_''et_al.'',_2004-5] 5.0 ^5.1 Molnar, R.E. History of monitors and their kin. Pianka, E.R., King, D. and King, R.A. (Editors) (編). Varanoid lizards of the world. Indiana University Press. 2004: 588 pp.

[Lee,_1999-6] Lee MSY. Possible affinities between Varanus giganteus and Megalania prisca. Memoirs of the Queensland Museum. 1996, 39: 232.

[Head_''et_al.'',_2009-7] Head, JJ.; Barrett, PM.; Rayfield, EJ. Neurocranial osteology and systematic relationships of Varanus (Megalania) prisca Owen, 1859 (Squamata: Varanidae). Zoological Journal of the Linnean Society. 2009, 2009 (155): 445–57.

[Hecht,_1975-8] Hecht, M. The morphology and relationships of the largest known terrestrial lizard, Megalania prisca Owen, from the Pleistocene of Australia. Proceedings of the Royal Society of Victoria. 1975, 87: 239–50.

[Wroe,_2002-9] 9.0 ^9.1 ^9.2 Wroe, S. A review of terrestrial mammalian and reptilian carnivore ecology in Australian fossil faunas, and factors influencing their diversity: the myth of reptilian domination and its broader ramifications (PDF). Australian Journal of Zoology. 2002, 50: 1–24 [2009-09-28]. （原始內容 (PDF)存檔於2003-12-10）.

[Wroe_''et_al.'',_2004-10] Wroe S, Field J, Fullagar R, & Jermiin LS. Megafaunal extinction in the late Quaternary and the global overkill hypothesis. Alcheringa. 2004, 28: 291–331.

[Wroe_''et_al.'',_1999-11] Wroe S, Myers TJ, Wells RT & Gillespie, A. Estimating the weight of the Pleistocene marsupial lion, Thylacoleo carnifex (Thylacoleonidae : Marsupialia): implications for the ecomorphology of a marsupial super-predator and hypotheses of impoverishment of Australian marsupial carnivore faunas. Australian Journal of Zoology. 1999, 47: 489–98.

[12] Flannery T. The Future Eaters. 1994: pp. 384–5. ISBN 0-8021-3943-4.

[Fry2006-13] Fry, B.; et al. Early evolution of the venom system in lizards and snakes. Nature. February 2006, 439: 584–8 [2009-09-28]. doi:10.1038/nature04328. （原始內容存檔於2009-04-19）.

[14] Komodo Dragons Kill With Venom, Researchers Find （頁面存檔備份，存於網際網路檔案館） (National Geographic)

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