Hypsilophodon (Hypsilophodon foxii) belongs to the family Hypsilophodontidae and lived approximately 125 to 113 million years ago. Its name translates to "high-crested tooth," referring to the distinctive dental features observed in some specimens. The first Hypsilophodon fossils were discovered in 1849 on the Isle of Wight, England.

Hypsilophodon was a small dinosaur, measuring around 1.2 to 2.3 meters in length and weighing approximately 20 to 40 kilograms. It possessed a slender build with long hind limbs and a relatively long tail, indicating its agility and efficient bipedal locomotion. Hypsilophodon had a small head with a pointed snout, and its teeth were specialized for slicing through plant material. It also featured a prominent thumb claw that likely served a functional purpose, possibly for defense or grasping vegetation.