Iguanodon was a large herbivorous dinosaur that lived during the Early Cretaceous period, approximately 140 to 125 million years ago. Measuring up to 10 meters (33 feet) in length and weighing around 3.5 metric tons, Iguanodon was one of the first dinosaurs ever discovered and described. It was characterized by its robust body, long tail, and distinctive thumb spikes, which may have been used for defense against predators. Iguanodon had a beak-like mouth for cropping vegetation and a complex set of teeth for grinding plant material. Fossils of Iguanodon have been found in Europe and North America, providing valuable insights into the early evolution of ornithopod dinosaurs.