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. The type species is A. calvoi, and is the only known species of the genus so far.
Description[]
Restoration.
Alvarezsaurus was a small theropod with a single claw on each hand, a long tail, and a very feathery coat. Its leg structure also suggests a lifestyle of fast running, either used for evading predators or chasing prey; it is unknown which of these two uses the speed was prioritized for. Estimates measure the creature at about 2 meters (6.5 ft) in length and weighed approximately 20 kg (45 lbs).
Given its morphology and related genera, it was likely an insectivore, but may have also hunted small animals as well.
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.
Dinosaur Earth Description[]
Alvarezsaurus was a small South American bird-like dinosaur that was a plant eater. What makes this strange is that it belongs to the family of dinosaurs known as theropods. This family includes T. rex and Velociraptor. Until the last few years, it was believed that all theropods were meat eating dinosaurs. Recent discoveries like Alvarezsaurus and Therizinosaurus are leading scientists to believe that during the late Cretaceous some theropods became plant eaters. Until recently, Alvarezsaurus was considered by some to be more bird than dinosaur and it was often excluded from dinosaur genera. It was most likely feathered and looked like many of the ornithomimids. The most recent studies have placed it into the dinosaurian genera.
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