Andesaurus

• Argentina ( Candeleros Formation)

• Andesaurus delgadoi

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

So far, a fragmentary skeleton is only known that was found in the rock strata of the Candeleros Formation in the Argentine province of Neuquén. Known parts of the dorsal and caudal spine, pelvic bones, and the upper portions of the legs. The only way is Andesaurus delgadoi. Andesaurus is considered the most primitive representatives of Titanosauria.

Features

Andesaurus was a great representative of the Titanosauria. It can be distinguished only by a single characteristic of other genera ( autapomorphy ): So the spinous processes of the posterior dorsal vertebrae were extended and two times as high as the respective vertebral bodies. Although elongated spinous processes occur in various other sauropods, came from representatives of Titanosauria virtually no spinous before that were more than 1.5 times as long as the vertebral body. Most of the other members of the Titanosauria to Andesaurus also differs by the presence of Hyposphen - Hypantrum connections, additional mechanical connecting elements of the vertebrae. This original feature occurred in Andesaurus and primitive sauropod and contributed to the stabilization of the spine. Most Titanosauria these compounds have, however, lost in favor of a more flexible spine. Another original feature is the flattened on both sides ( amphiplatischen ) caudal vertebrae: To view advanced Titanosaurier procoele caudal vertebrae, the strongly concave and on the back were correspondingly convex on the front page.

System

In contrast to many other genres of Titanosauria, their relationships with each other are unclear, the position of Andesaurus than most original or one of the most original Titanosauria is undisputed. However, Bonaparte and Calvo (1991 ) found this genus in the Titanosauridae ( = Lithostrotia ), they arranged within this family a new subfamily to which Andesaurinae that should be distinguished from other titanosaurs by various primitive features. Bonaparte and Coria (1993 ) defined the Andesaurinae as a separate family, the Andesauridae, and ordered her to Andesaurus and Argentinosaurus. The Andesauridae should face as a primitive Titanosaurierfamilie the more advanced Titanosauridae. Today, however, the Andesauridae regarded as paraphyletic ( Andesaurus and Argentinosaurus were non- self-contained group) and thus invalid.

Fund, Research History and naming

The only known skeleton was discovered in May 1987 near El Chocón in Neuquén, from a field trip to the Museo de Ciencias Naturales of Universidad Nacional del Comahue with the technical support of the Museo Argentino de Ciencias Naturales. The fossils are from the Candeleros lineup, the oldest layer member of the Neuquén Group. The Fund ( holotype ) is partial skeleton consisting of 4 associated posterior dorsal vertebrae, 27 associated, obtained in two blocks remaining caudal vertebrae of the middle and anterior part of the tail, as well as some almost complete pelvic bones - the ischium ( ischium ) and pubis ( pubic ) - and from fragmentary leg bones - the humerus (humerus ) and the thigh bone ( femur) is. The findings were described in 1991 by Jorge Calvo and José Fernando Bonaparte first time scientifically. Upchurch and colleagues ( 2004) indicate that Andesaurus is potentially important because of its basal position within the Titanosauria for understanding the evolution of these sauropods. However, the first description is merely short and insufficient, a more extensive description is pending.

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

Documents

Main source

• J. O. Calvo, J. F. Bonaparte. In 1991. Andesaurus delgadoi Gen. et sp. nov. ( Saurischia, Sauropoda ), dinosaurio Titanosauridae de la Formacion Rio Limay ( Albiano - Cenomaniano ), Neuquén, Argentina [ Andesaurus delgadoi Gen. et sp. nov. ( Saurischia, Sauropoda ), a titnosaurid dinosaur from Rio Limay Formation ( Albian - Cenomanian ), Neuquén, Argentina ]. Ameghiniana 28 (3-4 ), pages 303-310