Edmontosaurus was one of the last of the Dinosaurs that lived during the late Cretaceous period. It lived in North America alongside Triceratops, Dromaeosaurs, and T-Rex. The name Edmontosaurus means lizard of Edmonton and with it's broad, flat nose it certainly looked just like a giant duck. Edmontosaurus is an example of the "duckbill" snout common to hadrosaurs. Edmontosaurus was about 28-40 feet long stood was 17 feet tall and weighed about 3-5 tons. It was a type of specialized hadrosaur that thrived in woodlands and tropical types of environments. Edmontosaurus has a long and complex taxonomic history dating to the 19th century when remains were first discovered by Cope in 1871. Remains of Edmontosaurus have been described as different species including Anatosaurus, Anatotitan, Claosaurus, Diclonius, Hadrosaurus, Thespesius, and Trachodon. The best and most recent example is Anatosaurus and Anatotitan which are now considered by most paleontologists today as synonyms of Edmontosaurus.
E. annectens was a saurolophine or "flat-headed" hadrosaurid; this group was historically known as Hadrosaurinae. However, the skull of the sub-adult type specimen of E. annectens differs from full blown adult skulls, so many paleontologists in the past had classified the two growth stages as separate species. Species now classified as Edmontosaurus annectens were once considered for a long time as different but related species. The first paleontologist to suggest that these are all one species was John Bell Hatcher in 1902. In 2004 Jack Horner, David B. Weishampel, and Catherine Forster agreed with Hatchers research. Most recently Nicolás Campione and David Evans, concluded from analyzing the various skulls, that the large flat-headed specimens most recently assigned to Anatotitan copei actually belong to E. annectens.
Food and lifestyle
Edmontosaurus was a herbivorous dinosaur.It had a horny, toothless beak with cheeks containing hundreds of rows of teeth; 1,000 teeth total. It mainly ate pine needles, twigs, seeds, fruits and possibly dead wood and bark when softer food was scarce. Edmontosaurus lived in vast herds and would have been like the cretaceous version of a Zebra. It would have been common to see these dinosaurs grazing and ambling across the plains and forests of cretaceous North America, possibly alongside, fellow hadrosaurids Hypacrosaurus and Saurolophus, hypsilophodont Parksosaurus, horned dinosaurs Montanoceratops, Anchiceratops, Triceratops Arrhinoceratops, and Pachyrhinosaurus, pachycephalosaurid Stegoceras, ankylosaurid Euoplocephalus. Edmontosaurus and it's contemporaries would have had to watch their backs because there were many ferocious predatory dinosaurs roaming the land as well. These would have included Tyrannosaurids, Troodontids, and Dromaeosaurids. However Edmontosaurs were not as defenseless as they appeared. They were absolutely massive and with one strike of that 17 foot long tail could break bones. A mass grave discovery in Alberta, Canada suggests that Edmontosaurs lived in herds. A herd could also band together for protection against multiple predators. These herds may have migrated with the seasons, from the North Slope of Alaska, where plant life would have been hard to come by during the long dark winter, to the abundant pastures of Alberta and North America. While the Edmontosaurs migrated they most likely would have been stalked by T-rex and Dromaeosaurs.