Hypsilophodon roamed the Earth during the Early Cretaceous Period, and is considered to have belonged to the Ornithopoda, or bird-footed group.
The name Hypsilophodon comes from the shape of its teeth, which allowed it to grind up its food prior to swallowing it. This smaller dinosaur is one of very few reptiles to have had cheeks. A feature that allowed it to keep food stored in its mouth while it chewed, similar to how humans chew food today.
Hypsilophodon was discovered in 1869 by Gideon Mantall on England's Isle of Wight, or "Dinosaur Island."
For years scientists believed that Hypsilophodon may have lived in trees. However, this theory is no longer accepted today as accurate.