安第斯龍屬

? 編輯 安第斯龙 保护现状：化石 化石時期：上白堊紀
分类
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： 蜥臀目(Saurischia) 亞目： 蜥腳亞目(Sauropodomorpha) 下目： 蜥腳下目(Sauropoda)   巨龍科(Titanosauria) 科： 安第斯龍科(Andesauridae) 屬： 安第斯龍屬(Andesaurus) 種： 安第斯龍(A. delgadoi)
学名
Andesaurus delgadoi Calvo & Bonaparte, 1991

安第斯龙（學名Andesaurus）是巨龍科基底的一個屬，存在於白堊紀的南美洲。牠有著長頸與細少的頭，及相同長度的尾巴。安第斯龍是一種非常大型的蜥腳下目恐龍，就如牠的其他同科親屬一樣，都是地球最大型的生物之一。

命名

於1991年，古生物學家Jorge Calvo及約瑟·波拿巴（Jose Bonaparte）命名了安第斯龍，是指牠從接近安第斯山脈的地方被發現。安第斯龍的種（A. delgadoi）則是以發現牠的化石的Alejandro Delgado來命名。

化石及發現歷史

The only known material of Andesaurus is a partial skeleton consisting of a series of four vertebrae from the lower back, as well as 27 tail vertebrae, divided up into two series from separate parts of the tail. Elements of the pelvis were also discovered, including two ischia and a pubis bone, along with rib fragments and an incomplete humerus and femur.

These fossils were discovered in the Candeleros Formation, the oldest formation within the Neuquén Group of Neuquén Province, Argentina. This formation dates to the early Cenomanian stage of the Early Cretaceous Period, or about 100 to 97 million years ago. For the most part, the Candeleros represents an ancient braided river system, and besides Andesaurus, also contains fossils of theropods like Buitreraptor and the enormous Giganotosaurus, as well as other non-related sauropods such as Limaysaurus.

分類

Several plesiomorphic (primitive) features characterize Andesaurus as the most basal known member of Titanosauria. In fact, this clade has been defined to contain Andesaurus, Saltasaurus, their most recent common ancestor, and all of its descendants (Salgado et al., 1997; Wilson & Upchurch, 2003). The most prominent plesiomorphy is the articulations between its tail vertebrae. In most derived titanosaurs, the tail vertebrae articulate with ball-and-socket joints, with the hollowed-out socket end on the front (procoelous caudal vertebrae), while in Andesaurus, both ends of the vertebrae are flat (amphiplatyan caudals), as seen in many non-titanosaurian sauropods. Andesaurus itself is only characterized by a single feature, the tall neural spines on top of its back vertebrae, and needs further study (Upchurch et al., 2004).

Some other basal titanosaurs from Argentina, including Argentinosaurus and Puertasaurus, were also sauropods of enormous size. The most derived group of titanosaurs, the Saltasauridae, included some of the smallest known sauropods, including Saltasaurus itself. Thus it is possible that the largest sizes were attained among the more basal members of the clade (Novas et al., 2005).

參考

• Calvo, J.O. & Bonaparte, J.F. 1991. [Andesaurus delgadoi n. g. n. sp. (Saurischia, Sauropoda) a titanosaurid dinosaur from the Río Limay Formation (Albian-Cenomanian), Neuquén, Argentina.] Ameghiniana. 28: 303-310. [In Spanish]
• Novas, F.E., Salgado, L., Calvo, J.O., & Agnolin, F. 2005. Giant titanosaur (Dinosauria, Sauropoda) from the Late Cretaceous of Patagonia. Revista del Museum Argentino de Ciencias Naturales 7(1): 37-41.
• Salgado, L., Coria, R.A., & Calvo, J.O. 1997. Evolution of titanosaurid Sauropods. I: Phylogenetic analysis based on the postcranial evidence. Ameghiniana. 34: 3-32.
• Upchurch, P., Barrett, P.M, & Dodson, P. 2004. Sauropoda. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). The Dinosauria (2nd Edition). Berkeley: University of California Press. Pp. 259-322.
• Wilson, J.A. & Upchurch, P. 2003. A revision of Titanosaurus Lydekker (Dinosauria – Sauropoda), the first dinosaur genus with a ‘Gondwanan’ distribution. Journal of Systematic Palaeontology 1(3): 125–160.