Edmontosaurus, meaning “Edmonton lizard”, is a hadrosaurid from the Late Cretaceous period approximately 73-65 million years ago. Edmontosaurus has a complicated taxonomic history specimens of Edmontosaurus have been classified with various genera including Anatosaurus, Anatotitan, Claosaurus, Diclonius, Hadrosaurus, Thespesius, and Trachodon. Presently, Anatosaurus and Anatotitan are possible synonyms to Edmontosaurus. Edmontosaurus hails from Alberta, Canada in the Horeshoe Canyon Formation (originally known as the lower Edmonton Formation) and was discovered in 1917 by Lawrence Lambe. Remains, though unknown at the time, were first found of Edmontosaurus in 1892 by Othniel Charles Marsh. Marsh originally gave the name to these remains of Claosaurus, but later changed to Anatosaurus. Edmontosaurus reached sizes of anywhere between 9 meters (30 ft) long meters to 13 meters (43 ft) long and weighed anywhere around 4.0 metric tons (4.4 short tons). Edmontosaurus was encountered by Simon and his team while documenting Isla Sorna.