Argyrosaurus

• Argentina

• Argyrosaurus superbus

Argyrosaurus is a genus of sauropod dinosaur from the group of Titanosauria. Fossils of this genus are from the Late Cretaceous ( Campanian or Maastrichtian ) of Argentina.

Argyrosaurus 1893 described by Richard Lydekker on the basis of a foreleg first scientifically only way is Argyrosaurus superbus. Other bones that have been made to this genus, derived in particular from the Bajo- Barreal lineup. The name Argyrosaurus ( gr argyros - "silver", gr saura - "lizard ") means the same as " silver lizard", referring to the country Argentina ( "land of silver " ), where the fossils were found.

Features

Argyrosaurus was a great Titanosaurier. From other species it can be distinguished by particularly high and short vertebral arches. The from Elle ( ulna ) and radius ( radius) existing lower leg was robust, the metacarpal bones were long as with other representatives of the Macronaria. The upper arm bone (humerus ) shows a rectangular top, similar to the advanced ( derived ) titanosaurs Saltasaurus and Opisthocoelicaudia. An important feature that confirms the status within a Titanosauria ( synapomorphy ), is a more pronounced bone spur at the upper end of the ulna ( olecranon ).

Research history and validity of the genus

Richard Lydekker described Argyrosaurus 1893 based on an articulated forelimb including hand skeleton, which was discovered in the area of ​​the river Chubuts. In its first description, he ordered two more finds from other sites also to this genus. These finds - a thigh bone ( femur) from the Río Senguerr and two large tail vertebrae from Santa Cruz - were similar, according to Lydekker Although in color and mineral composition, but the assignment of these findings to Argyrosaurus could not be confirmed by recent studies. Powell (1986) and Bonaparte ( 1996) attributed this genus three dorsal vertebrae, three caudal vertebrae, a scapula, a humerus, radius and ulna of both front legs and thigh bone and shin bone (tibia) to which were found in the Bajo- Barreal lineup.

Upchurch and colleagues ( 2004) noted that this was the status of the genus doubtful. Thus, the only diagnostic features found on the anterior caudal vertebrae, but not part of the type series. Thus Argyrosaurus may need to be performed as a noun dubium ( dubious name) in the future.

System

The systematic position of this genus within the Titanosauria is unclear. Most of the authors Argyrosaurus was provided to the Titanosauridae, a group of advanced Titanosauria. The name Titanosauridae is not currently recognized by many researchers - instead, the name Lithostrotia was proposed. Upchurch and colleagues ( 2004) classify Argyrosaurus outside the Lithostrotia. Powell (1986 ) presented Argyrosaurus in its own subfamily, the Argyrosaurinae. The name Argyrosaurinae was indeed by some later authors used (eg, Bonaparte, 1996), but was not widely use.