Alvarezsaurus (/ˌælvərɛzˈsɔrəs/; "Alvarez's lizard") is a genus of small alvarezsaurid dinosaur from the Late Cretaceous period of Argentina, approximately 86 - 83 million years ago. Estimates suggest that it measured about 2 meters (6.5 ft) in length and weighed approximately 20 kg (45 lbs). It was found in the Bajo de la Carpa Formation and was named by paleontologist José Bonaparte in 1991 after the historian Don Gregorio Alvarez.
Description[]
The type species is A. calvoi. It was bipedal, had a long tail and its leg structure suggests that it was a fast runner. It may have been insectivorous and was basal to better-known members of its family, such as Mononykus and Shuvuuia. It has been alternately classified with both non-avian theropod dinosaurs and early birds.
Classification[]
Alvarezsaurus is considered basal to better-known members of its family, such as Mononykus and Shuvuuia. It has been alternately classified with both non-avian theropod dinosaurs and early birds, but a move of the alvarezsaurids to be recognized as more closely related to neornithine birds proved controversial despite being supported by earlier studies. It was once believed that the Patagonian alvarezsaur taxa were the most basal of their family, but the discovery of a more basal member, Haplocheirus, disproved that when its fossils were discovered in China.
In popular culture[]
Alvarezsaurus was featured in the Discovery Channel television series Dinosaur Planet, which speculated that it was a predator of young Saltasaurus, though these species did not exist at the same time, Alvarezsaurus being about 5 million years older than Saltasaurus.
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