Neuquensaurus (meaning "Neuquén lizard") is a genus of saltasaurid sauropod dinosaur that lived in the Late Cretaceous, about 80 million years ago in Argentina in South America. Its fossils were recovered from outcrops of the Anacleto Formation around Cinco Saltos, near the Neuquén river from which its name is derived.
In 1893, Richard Lydekker named Titanosaurus australis, based on a series of caudal vertebrae and limb elements. The remains had been found by Santiago Roth and F. Romero in the Neuquén Province of Argentina at the Neuquén River, and were by Lydekker assigned to a single individual.[1] Six caudal vertebrae, with the inventory numbers MLP Ly 1-6-V-28-1, were the holotype of the species. They had probably been found in a layer of the Anacleto Formation.
Some elements that had been referred to Titanosaurus australis were reassigned to Laplatasaurus araukanicus by Friedrich von Huene in 1929.[1] The same year, von Huene named a Titanosaurus robustus, and claimed it differed from T. australis in the limb material. Von Huene described all the slender limb material to T. australis, but did not identify any differentiating features between the vertebrae.[2] When describing T. robustus, von Huene did not really compare other genera and species to it.[1] From the syntype material assigned by von Huene to T. robustus José Fernando Bonaparte et al. in 1978 chose four lectotypes, specimens MLP 26-250, MLP 26-252, MLP 26-254, and MLP 26-259, a left femur, both ulnae, and a left radius.[3][1]
In 1986, Jaime Eduardo Powell, concluding that Titanosaurus australis was less similar than Laplatasaurus araukanicus to Titanosaurus indicus, named a separate genus: Neuquensaurus.[4] However, he did so in an unpublished dissertation which caused Neuquensaurus australis and Neuquensaurus robustus to remain invalid nomina ex dissertatione. In 1990, the two species were assigned to Saltasaurus by John Stanton McIntosh, as a Saltasaurus australis and a Saltasaurus robustus, claiming that the features found by Bonaparte were not of sufficient taxonomic importance to justify a generic separation.[1]
In 1992 Powell validly named Neuquensaurus, with as type species Titanosaurus australis of which the combinatio nova then is Neuquensaurus australis. He also found Titanosaurus robustus to be assignable to the new genus, but considered it non-diagnostical, and so a nomen dubium.[5]
This dinosaur is believed to have possessed armor-like osteoderms. A relatively small sauropod, with a femur only 0.75 metres (2.5 ft) long. It is one of the most completely known of Patagonian sauropods,[1] measuring 7–9 metres (23–30 ft) long and weighing 1.8–3.5 metric tons (2.0–3.9 short tons).[6][7] In addition to the original fossils described by Lydekker in 1893, it is represented by fossils collected in the early twentieth century, and more recent material, including a well preserved and partially articulated specimen described in 2005 (with two associated osteoderms).[8]