Edmontosaurus annectensEdmontosaurus annectens (meaning "connected lizard from Edmonton"), often colloquially and historically known as the Anatosaurus (meaning "duck lizard"), is a species of flat-headed saurolophine hadrosaurid dinosaur from the late Maastrichtian age at the very end of the Cretaceous period, in what is now western North America. Remains of E. annectens have been preserved in the Frenchman, Hell Creek, and Lance Formations.
Timeline of hadrosaur researchThis timeline of hadrosaur research is a chronological listing of events in the history of paleontology focused on the hadrosauroids, a group of herbivorous ornithopod dinosaurs popularly known as the duck-billed dinosaurs. Scientific research on hadrosaurs began in the , when Joseph Leidy described the genera Thespesius and Trachodon based on scrappy fossils discovered in the western United States. Just two years later he published a description of the much better-preserved remains of an animal from New Jersey that he named Hadrosaurus.
EdmontosaurusEdmontosaurus (ɛdˌmɒntəˈsɔːrəs ) (meaning "lizard from Edmonton"), often colloquially and historically known as Anatosaurus (meaning "duck lizard"), is a genus of hadrosaurid (duck-billed) dinosaur It contains two known species: Edmontosaurus regalis and Edmontosaurus annectens. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian age of the Cretaceous period 73 million years ago, while those of E.
TrachodonTrachodon (meaning "rough tooth") is a dubious genus of hadrosaurid dinosaur based on teeth from the Campanian-age Upper Cretaceous Judith River Formation of Montana, U.S. It is a historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists. Despite being used for decades as the iconic duckbill dinosaur, the material it is based on is composed of teeth from both duckbills and ceratopsids (their teeth have a distinctive double root), and its describer, Joseph Leidy, came to recognize the difference and suggested limiting the genus to what would now be seen as ceratopsid teeth.
HadrosaurusHadrosaurus (ˌhædrəˈsɔːrəs; bulky lizard) is a genus of hadrosaurid ornithopod dinosaurs that lived in North America during the Late Cretaceous Period in what is now the Woodbury Formation about 78-80 Ma. The holotype specimen was found in fluvial marine sedimentation, meaning that the corpse of the animal was transported by a river and washed out to sea. They were large animals ranging from and . Most of the preserved elements are very robust, unusual traits in hadrosaurs.