Hypsilophodon was a small, herbivorous dinosaur that lived during the Early Cretaceous period, around 130 million years ago. It was about 2 to 3 meters long and walked on two legs, although it could also move on all fours. Its lightweight body and long legs suggest it was a fast runner, likely using speed to escape predators. This dinosaur had a beak-like mouth and small, leaf-shaped teeth, ideal for eating plants. Fossils of Hypsilophodon have been found primarily in England, providing valuable insights into the diversity of small dinosaurs during its time.