Parksosaurus was one of the last members of the hypsilophodont family. They lived about 70 million years ago. These small dinosaurs were up to 10 feet long and about 130 pounds. Like Dryosaurus, Parksosaurus would have been able to run quite fast, perhaps as fast as 30 miles per hour. Parksosaurus would have been easy prey for many of the smaller predators in the area. They lived in North America.