原駝龍屬

原駝龍屬; 化石時期：晚白堊世，森諾曼階–土侖階 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：	蜥形綱 Sauropsida
總目：	恐龍總目 Dinosauria
目：	†鳥臀目 Ornithischia
亞目：	†鳥腳亞目 Ornithopoda
演化支：	†薄板類 Elasmaria
屬：	†原駝龍屬 Chakisaurus; Alvarez Nogueira et al., 2024
模式種
	†迅捷原駝龍; Chakisaurus nekul; Alvarez Nogueira et al., 2024

原駝龍（屬名：Chakisaurus，意為「更古老的羊駝」）是來自阿根廷晚白堊世烏因庫爾組（英語：Huincul Formation）的一屬已滅絕薄板類。屬下包括單一物種迅捷原駝龍（C. nekul），所知於多具不同年齡的個體。原駝龍代表自烏因庫爾組命名的首個鳥臀目物種。

發現與命名

位於阿根廷普布韋洛布蘭科自然保護區的原駝龍模式產地

原駝龍化石材料發現於阿根廷內格羅河省埃茲奎爾拉莫斯梅西亞湖（Ezequiel Ramos-Mexía Lake）附近普布韋洛布蘭科自然保護區（英語：Pueblo Blanco Natural Reserve）（以前稱作維奧蘭特農場地）烏因庫爾組（英語：Huincul Formation）的沉積物中。正模標本MPCA Pv 816由幾節部分背椎、部分骶骨、12節尾椎、一個不完整的髓弓（英語：haemal arch）、部分左股骨和腓骨、部分右脛骨和跟骨（英語：calcaneus）及兩節第四趾趾骨組成。另有三件額外副模標本（英語：paratype）歸入該屬，均在約500米（1,600英尺）內成堆出現。第一件是MPCA Pv 822，屬於一隻幼年個體，包含5個背椎椎體、一個左肱骨及兩個股骨底部。第二件標本MPCA Pv 823同為幼龍，包括一個右尺骨頂端。第三件是MPCA Pv 813，包括8個背椎椎體、2根部分肋骨、2個部分髓弓、右橈骨底部、一節第四趾趾骨及一隻第二或第四趾的腳爪（英語：ungual）。一節額外的頸椎（可能是第四節）即MPCN Pv 846亦歸入該屬。^[1]

2024年，阿爾瓦雷斯·諾蓋拉（Alvarez Nogueira ）等人據此化石遺骸描述了鳥腳類新屬新種迅捷原駝龍（Chakisaurus nekul）。屬名組合特維爾切語（英語：Aonikenk）「Chaki」（意為「更古老的羊駝」，這裏指原駝）及希臘語「σαῦρος」（sauros，意為「蜥蜴」）一詞。種名在馬普切語中意為「敏捷的」。^[1]

原駝龍代表從南美洲命名的第10種原始鳥腳類。^[1]

描述

原駝龍被描述為一種「中型」薄板類鳥腳下目，體型與阿納拜斯龍、南方棱齒龍、特立尼龍等分類單元相仿，但比小頭龍、嶺奔龍、伊薩西奔龍等分類單元更小。對該物種保存下來的後肢骨骼進行分析，未發現對某種程度上四足步行的適應性，表明某些其它薄板類是獨立進化出這些特徵的。^[1]

前段尾椎關節彈性連接，可能導致一種尾基部下彎的傾斜姿勢。該特徵曾僅在泰坦巨龍類中觀察到，包括風神龍族的阿魯達巨龍。像其它薄板類一樣，尾部具有和某些虛骨龍類獸腳亞目相似的對行走的適應性。^[1]^[2]^[3]

分類

阿爾瓦雷斯·諾蓋拉等人（2024年）在系統發育分析中將本屬恢復為一種薄板類鳥腳亞目恐龍，而薄板類又隸屬禽龍類演化支橡樹龍形態類。他們指出，由於原駝龍化石材料破碎，其演化樹尚不夠精確。結果如以下分支圖所示：^[1]

腱龍各物種 Tenontosaurus spp.

禽龍類 Iguanodontia

木他龍 Muttaburrasaurus

	維格蓋特（英語：Castrillo de la Reina Formation）的鳥腳類 Vegagete ornithopod

	福斯特龍 Fostoria

	凹齒龍科 Rhabdodontidae

橡樹龍形態類 Dryomorpha

橡樹龍 Dryosaurus

	荒漠龍 Valdosaurus

	難捕龍 Dysalotosaurus

隱士彎龍（猶他齒龍） Camptosaurus aphanoecetes

	貝尼薩特禽龍 Iguanodon bernissartensis

	全異彎龍 Camptosaurus dispar

東橡樹龍 Eousdryosaurus

薄板類 Elasmaria

小頭龍 Talenkauen

	原駝龍 Chakisaurus

	莫羅龍 Morrosaurus

	嶺奔龍 Mahuidacursor

	巨謎龍 Macrogryphosaurus

	康納龍 Kangnasaurus

	阿納拜斯龍 Anabisetia

古生態學

原駝龍發現於阿根廷內格羅河省晚白堊世烏因庫爾組（英語：Huincul Formation）。包括雷巴齊斯龍科（鷲龍、利邁河龍及星脈龍）、^[4]^[5]泰坦巨龍類（阿根廷龍、巴斯汀格里巨龍、堅毅龍及喬岡龍）、^[6]鯊齒龍科（馬普龍、米拉西斯龍及牛獵龍）、^[7]一種大盜龍類（南盜龍）、阿貝力龍科（蠍獵龍、雷霆龍及肌肉龍）、一種輕龍亞科（烏因庫爾龍）、^[8]一種近鳥類（斑盜龍）及獨特鳥獸腳類瓜利喬龍在內的多種蜥臀目恐龍同樣是從該組中命名。^[9]^[10]一種未命名半鳥科的遺骸亦被報道。^[11]非恐龍動物群包括化石魚類、楔齒蜥類、分類不明的有鱗目、蛇頸龜科及真鱷類。^[1]

原駝龍是該地層首個獲得學名的鳥臀目，此前這裏發現的唯一鳥臀目骨骼是一隻分類不明鳥腳類的爪子。^[1]

參考資料

^ ^1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 ^1.6 ^1.7 Alvarez-Nogueira, Rodrigo; Rozadilla, Sebastián; Agnolín, Federico L.; Garcia Marsà, Jordi A.; Motta, Matias J.; Novas, Fernando E. A new ornithopod from the Upper Cretaceous (Huincul Formation) of Northwestern Patagonia, Argentina. Implications on elasmarian postcranial anatomy. Cretaceous Research. 2024-03-11, 159 (In press): 105874. doi:10.1016/j.cretres.2024.105874.
^ Vidal, Luciano da Silva; Pereira, Paulo Victor Luiz Gomes da Costa; Tavares, Sandra; Brusatte, Stephen L.; Bergqvist, Lílian Paglarelli; Candeiro, Carlos Roberto dos Anjos. Investigating the enigmatic Aeolosaurini clade: the caudal biomechanics of Aeolosaurus maximus (Aeolosaurini/Sauropoda) using the neutral pose method and the first case of protonic tail condition in Sauropoda. Historical Biology. 2021-09-02, 33 (9): 1836–1856. Bibcode:2021HBio...33.1836V. ISSN 0891-2963. doi:10.1080/08912963.2020.1745791 （英語）.
^ Rozadilla, Sebastián; Cruzado-Caballero, Penélope; Calvo, Jorge O. Osteology of Ornithopod Macrogryphosaurus gondwanicus (Dinosauria, Ornithischia) from the Upper Cretaceous of Patagonia, Argentina. Cretaceous Research. 2020, 108: 104311 [2024-04-15]. Bibcode:2020CrRes.10804311R. S2CID 213679041. doi:10.1016/j.cretres.2019.104311. （原始內容存檔於2020-07-25）.
^ Calvo, Jorge O.; Salgado, Leonardo. Rebbachisaurus tessonei sp. nov. a new Sauropoda from the Albian-Cenomanian of Argentina; new evidence on the origin of the Diplodocidae (PDF). Gaia. 1995, 11: 13–33. （原始內容 (PDF)存檔於23 September 2021）.
^ Lerzo, Lucas Nicolás; Gallina, Pablo Ariel; Canale, Juan Ignacio; Otero, Alejandro; Carballido, José Luis; Apesteguía, Sebastián; Makovicky, Peter Juraj. The last of the oldies: a basal rebbachisaurid (Sauropoda, Diplodocoidea) from the early Late Cretaceous (Cenomanian–Turonian) of Patagonia, Argentina. Historical Biology. 2024-01-03: 1–26. ISSN 0891-2963. doi:10.1080/08912963.2023.2297914 （英語）.
^ Simón, M. E.; Salgado, L. A new gigantic titanosaurian sauropod from the early Late Cretaceous of Patagonia (Neuquén Province, Argentina). Acta Palaeontologica Polonica. 2023. doi:10.4202/app.01086.2023 .
^ Canale, Juan I.; Apesteguía, Sebastián; Gallina, Pablo A.; Mitchell, Jonathan; Smith, Nathan D.; Cullen, Thomas M.; Shinya, Akiko; Haluza, Alejandro; Gianechini, Federico A.; Makovicky, Peter J. New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction. Current Biology. July 2022, 32 (14): 3195–3202.e5. Bibcode:2022CBio...32E3195C. PMID 35803271. S2CID 250343124. doi:10.1016/j.cub.2022.05.057 .
^ Baiano, Mattia A.; Coria, Rodolfo A.; Cau, Andrea. A new abelisauroid (Dinosauria: Theropoda) from the Huincul Formation (lower Upper Cretaceous, Neuquén Basin) of Patagonia, Argentina. Cretaceous Research. June 2020, 110: 104408. Bibcode:2020CrRes.11004408B. S2CID 214118853. doi:10.1016/j.cretres.2020.104408.
^ Cerroni, M.A.; Motta, M.J.; Agnolín, F.L.; Aranciaga Rolando, A.M.; Brissón Egli, F.; Novas, F.E. A new abelisaurid from the Huincul Formation (Cenomanian-Turonian; Upper Cretaceous) of Río Negro province, Argentina. Journal of South American Earth Sciences. 2020, 98: 102445. Bibcode:2020JSAES..9802445C. S2CID 213781725. doi:10.1016/j.jsames.2019.102445.
^ Matías J. Motta; Federico L. Agnolín; Federico Brissón Egli; Fernando E. Novas. New theropod dinosaur from the Upper Cretaceous of Patagonia sheds light on the paravian radiation in Gondwana. The Science of Nature. 2020, 107 (3): Article number 24. Bibcode:2020SciNa.107...24M. PMID 32468191. S2CID 218913199. doi:10.1007/s00114-020-01682-1. hdl:11336/135530 .
^ Agnolin, Federico L.; Gonzalez Riga, Bernardo J.; Aranciaga Rolando, Alexis M.; Rozadilla, Sebastián; Motta, Matías J.; Chimento, Nicolás R.; Novas, Fernando E. A new giant titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Northwestern Patagonia, Argentina. Cretaceous Research. 2023-02-02, 146: 105487. Bibcode:2023CrRes.14605487A. ISSN 0195-6671. doi:10.1016/j.cretres.2023.105487 （英語）.

[Chakisaurus-1] 1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 ^1.6 ^1.7 Alvarez-Nogueira, Rodrigo; Rozadilla, Sebastián; Agnolín, Federico L.; Garcia Marsà, Jordi A.; Motta, Matias J.; Novas, Fernando E. A new ornithopod from the Upper Cretaceous (Huincul Formation) of Northwestern Patagonia, Argentina. Implications on elasmarian postcranial anatomy. Cretaceous Research. 2024-03-11, 159 (In press): 105874. doi:10.1016/j.cretres.2024.105874.

[Vidal2020_Biomech-2] Vidal, Luciano da Silva; Pereira, Paulo Victor Luiz Gomes da Costa; Tavares, Sandra; Brusatte, Stephen L.; Bergqvist, Lílian Paglarelli; Candeiro, Carlos Roberto dos Anjos. Investigating the enigmatic Aeolosaurini clade: the caudal biomechanics of Aeolosaurus maximus (Aeolosaurini/Sauropoda) using the neutral pose method and the first case of protonic tail condition in Sauropoda. Historical Biology. 2021-09-02, 33 (9): 1836–1856. Bibcode:2021HBio...33.1836V. ISSN 0891-2963. doi:10.1080/08912963.2020.1745791 （英語）.

[3] Rozadilla, Sebastián; Cruzado-Caballero, Penélope; Calvo, Jorge O. Osteology of Ornithopod Macrogryphosaurus gondwanicus (Dinosauria, Ornithischia) from the Upper Cretaceous of Patagonia, Argentina. Cretaceous Research. 2020, 108: 104311 [2024-04-15]. Bibcode:2020CrRes.10804311R. S2CID 213679041. doi:10.1016/j.cretres.2019.104311. （原始內容存檔於2020-07-25）.

[clavo&salgado1995-4] Calvo, Jorge O.; Salgado, Leonardo. Rebbachisaurus tessonei sp. nov. a new Sauropoda from the Albian-Cenomanian of Argentina; new evidence on the origin of the Diplodocidae (PDF). Gaia. 1995, 11: 13–33. （原始內容 (PDF)存檔於23 September 2021）.

[Sidersaura-5] Lerzo, Lucas Nicolás; Gallina, Pablo Ariel; Canale, Juan Ignacio; Otero, Alejandro; Carballido, José Luis; Apesteguía, Sebastián; Makovicky, Peter Juraj. The last of the oldies: a basal rebbachisaurid (Sauropoda, Diplodocoidea) from the early Late Cretaceous (Cenomanian–Turonian) of Patagonia, Argentina. Historical Biology. 2024-01-03: 1–26. ISSN 0891-2963. doi:10.1080/08912963.2023.2297914 （英語）.

[Bustingorrytitan-6] Simón, M. E.; Salgado, L. A new gigantic titanosaurian sauropod from the early Late Cretaceous of Patagonia (Neuquén Province, Argentina). Acta Palaeontologica Polonica. 2023. doi:10.4202/app.01086.2023 .

[Meraxes1-7] Canale, Juan I.; Apesteguía, Sebastián; Gallina, Pablo A.; Mitchell, Jonathan; Smith, Nathan D.; Cullen, Thomas M.; Shinya, Akiko; Haluza, Alejandro; Gianechini, Federico A.; Makovicky, Peter J. New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction. Current Biology. July 2022, 32 (14): 3195–3202.e5. Bibcode:2022CBio...32E3195C. PMID 35803271. S2CID 250343124. doi:10.1016/j.cub.2022.05.057 .

[coria2020-8] Baiano, Mattia A.; Coria, Rodolfo A.; Cau, Andrea. A new abelisauroid (Dinosauria: Theropoda) from the Huincul Formation (lower Upper Cretaceous, Neuquén Basin) of Patagonia, Argentina. Cretaceous Research. June 2020, 110: 104408. Bibcode:2020CrRes.11004408B. S2CID 214118853. doi:10.1016/j.cretres.2020.104408.

[cerroni2020-9] Cerroni, M.A.; Motta, M.J.; Agnolín, F.L.; Aranciaga Rolando, A.M.; Brissón Egli, F.; Novas, F.E. A new abelisaurid from the Huincul Formation (Cenomanian-Turonian; Upper Cretaceous) of Río Negro province, Argentina. Journal of South American Earth Sciences. 2020, 98: 102445. Bibcode:2020JSAES..9802445C. S2CID 213781725. doi:10.1016/j.jsames.2019.102445.

[Overoraptor-10] Matías J. Motta; Federico L. Agnolín; Federico Brissón Egli; Fernando E. Novas. New theropod dinosaur from the Upper Cretaceous of Patagonia sheds light on the paravian radiation in Gondwana. The Science of Nature. 2020, 107 (3): Article number 24. Bibcode:2020SciNa.107...24M. PMID 32468191. S2CID 218913199. doi:10.1007/s00114-020-01682-1. hdl:11336/135530 .

[Chucarosaurus-11] Agnolin, Federico L.; Gonzalez Riga, Bernardo J.; Aranciaga Rolando, Alexis M.; Rozadilla, Sebastián; Motta, Matías J.; Chimento, Nicolás R.; Novas, Fernando E. A new giant titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Northwestern Patagonia, Argentina. Cretaceous Research. 2023-02-02, 146: 105487. Bibcode:2023CrRes.14605487A. ISSN 0195-6671. doi:10.1016/j.cretres.2023.105487 （英語）.

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