Claim: Alectrosaurus, which is a medium-sized herbivore from the Late Cretaceous period, was discovered by George Olsen while on the Third Asiatic Expedition of the American Museum of Natural History in 1923.
Evidence: Alectrosaurus (/əˌlɛktroʊˈsɔːrəs/; meaning "alone lizard") is a genus of tyrannosauroid theropod dinosaur that lived in Asia during the Late Cretaceous period, about some 96 million years ago in what is now the Iren Dabasu Formation. It was a medium-sized, moderately-built, ground-dwelling, bipedal carnivore, estimated at 5 to 6 m (16 to 20 ft) with a body shape similar to its much larger advanced relative, Tyrannosaurus. On April 25, assistant paleontologist George Olsen excavated and recovered the holotype AMNH 6554, a nearly complete right hindlimb. In 1923, the Third Asiatic Expedition of the American Museum of Natural History, led by chief paleontologist Walter W. Granger was hunting for dinosaur fossils in Mongolia.