Hadrosaurids, 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, duck-like snouts and varied dental structures, which allowed them to efficiently chew tough plant material. Hadrosaurids were social animals, often found in large herds, and they inhabited a range of environments, from coastal plains to forests. These dinosaurs are part of the larger clade called Ornithopoda, which includes other bipedal herbivores. Notable genera include Hadrosaurus and Parasaurolophus, the latter known for its distinctive, elongated crest. Fossils of hadrosaurids have been discovered across North America, Europe, and Asia, providing valuable insights into their behavior and ecology.