Hadrosaurs, commonly known as "duck-billed dinosaurs," were a group of herbivorous dinosaurs that lived during the Late Cretaceous period, around 75 to 80 million years ago. They are characterized by their flat, broad snouts that resemble a duck's bill, which helped them efficiently graze on plants. Hadrosaurs were among the most successful dinosaurs, with many species identified, including Parasaurolophus and Edmontosaurus. These dinosaurs were typically large, reaching lengths of up to 40 feet. They had strong legs for running and were often social animals, living in herds. Hadrosaurs also possessed unique features, such as elaborate crests on their heads, which may have been used for communication or attracting mates. Their fossils have been found in various locations, providing valuable insights into their behavior and environment.