Andesaurus

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Andesaurus
Temporal occurrence
Upper Cretaceous (early Cenomanian )
100.5 to 96.2 million years
Locations
Systematics
Dinosaur (dinosauria)
Sauropods (Sauropoda)
Macronaria
Titanosaurs (Titanosauria)
Andesaurus
Scientific name
Andesaurus
Calvo & Bonaparte , 1991
Art
  • Andesaurus delgadoi

Andesaurus is a genus of sauropod dinosaur from the Titanosauria group that lived during the Early Upper Cretaceous (early Cenomanium ).

So far, only a fragmentary skeleton is known that was found in the rock layers of the Candeleros Formation in the Argentine province of Neuquén . Parts of the back and tail spine, pelvic bones and the upper sections of the legs are known. The only species is Andesaurus delgadoi . Andesaurus is considered to be the most original representative of the Titanosauria.

features

Andesaurus was a great representative of the Titanosauria. It can only be distinguished from other genera by a single feature ( autapomorphy ): The spinous processes of the posterior vertebrae were elongated and twice as high as the respective vertebral bodies. Although elongated spinous processes occur in various other sauropods, in representatives of the Titanosauria there were practically no spinous processes that were more than 1.5 times as long as the vertebral bodies. Andesaurus differs from most of the other representatives of the Titanosauria in the presence of hyposphene-hypantrum connections , additional mechanical connecting elements of the vertebrae. This original trait occurred in Andesaurus and more primitive sauropods and helped stabilize the spine. Most titanosaurs, however, have lost these connections in favor of a more flexible spine. Another, original feature are the flattened (amphipathic) caudal vertebrae: more advanced titanosaurs show procoele caudal vertebrae that were strongly concave on the front and correspondingly convex on the back.

Systematics

In contrast to many other genera of the Titanosauria, the relationships between which are unclear, the position of Andesaurus as the most original or one of the most original Titanosauria is undisputed. Bonaparte and Calvo (1991) assigned this genus to the Titanosauridae (= Lithostrotia ), but assigned it to a new subfamily within this family , the Andesaurinae, which is supposed to distinguish itself from other titanosaurs by various primitive features. Bonaparte and Coria (1993) defined the Andesaurinae as a separate family, the Andesauridae, and assigned them to Andesaurus and Argentinosaurus . The Andesauridae, as a more primitive titanosaur family, should face the more advanced Titanosauridae. Today, however, the Andesauridae are considered paraphyletic ( Andesaurus and Argentinosaurus did not form a self-contained group) and therefore invalid.

Find, research history and naming

The only known skeleton was discovered in May 1987 near El Chocón in Neuquén, during an excursion by the Museo de Ciencias Naturales of the Universidad Nacional del Comahue with technical support from the Museo Argentino de Ciencias Naturales . The fossils come from the Candeleros Formation , the oldest member of the Neuquén group . The Fund (holotype) is part skeleton associated with 4 rear vertebrae, associates 27, obtained in two blocks remaining caudal vertebrae of the middle and front part of the tail, as well as from some almost complete pelvic bone - the seat leg (ischium) and the pubic bone (pubis) - and consists of fragmentary leg bones - the upper arm bone ( humerus ) and the thigh bone (femur). The finds were scientifically described for the first time in 1991 by Jorge Calvo and José Fernando Bonaparte . Upchurch and colleagues (2004) state that Andesaurus is potentially important for understanding the evolution of these sauropods because of its basal position within the Titanosauria. However, the initial description is only brief and inadequate, a more comprehensive description is still pending.

The name Andesaurus ("Andean lizard") refers to the Andes mountain range where the fossils were found. The Artepitheth delgadoi honors Alejandro Delgado, who discovered the fossils.

supporting documents

Main source

  • Jorge O. Calvo , José F. Bonaparte : Andesaurus delgadoi gen. Et sp. nov. (Saurischia-Sauropoda), dinosaurio Titanosauridae de la Formacion Rio Limay (Albiano-Cenomaniano), Neuquén, Argentina. In: Ameghiniana . Vol. 28, No. 3/4, 1991, pp. 303-310, online .

Individual evidence

  1. ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 205, online .
  2. ^ A b c Paul Upchurch , Paul M. Barrett , Peter Dodson : Sauropoda. In: David B. Weishampel , Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 259-324.
  3. Jeffrey A. Wilson: An Overview of Titanosaur Evolution and Phylogeny. In: Fidel Torcida Fernández-Baldor, Pedro Huerta Hurtado (eds.): Actas de las III Jornadas Internacionales sobre Paleontología de Dinosaurios y Su Entorno. = Proceedings of the 3rd International Symposium about Paleontology of Dinosaurs and their Environment Paleontología de dinosaurios y su entorno. Salas de los Infantes (Burgos, España), 16 al 18 de septiembre de 2004. Colectivo arqueológico-paleontológico de Salas, Salas de los Infantes (Burgos, España) 2006, ISBN 84-8181-227-7 , pp. 169-190 .
  4. Leonardo Salgado , Rodolfo A. Coria , Jorge O. Calvo : Evolution of Titanosaurid Sauropods. I: Phylogenetic Analysis Based on the Postcranial Evidence. In: Ameghiniana . Vol. 34, No. 1, 1997, pp. 3–32, digitized version (PDF; 4.42 MB) ( Memento of the original from March 9, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / www.proyectodino.com.ar