The herbivorous ornithopods lived the longest, from the Early Jurassic to the Late Cretaceous period. They include a series of successively larger and more massive dinosaurs that spread throughout most of the continents. One was the Heterodontosaurus of the Early Jurassic period, a quick, 4-foot (1.3-meter) dinosaur, with strong front canine tusks and flexible hands used for digging and gasping vegetation.