Hadrosaurs, commonly known as "duck-billed dinosaurs," were a group of herbivorous dinosaurs that lived during the Late Cretaceous period. 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 common dinosaurs of their time and could be found in various habitats. These dinosaurs were known for their unique dental structures, which included hundreds of teeth that allowed them to chew tough vegetation. Some hadrosaurs, like Parasaurolophus, had distinctive crests on their heads, which may have been used for communication or display. Their social behavior often involved living in herds for protection against predators.