The psittacosaurids are considered the ancestors of the ceratopids, horned dinosaurs which include large animals such as the Triceratops. The name, “parrot lizard” comes from the powerful horny, toothless beak which characterizes the group. These dinosaurs are found only in China and Mongolia, but in large numbers. Probably Psittacosaurus evolved from Hypsilophodon, being able like this Hypsilophodon to mantain a bipedal posture while running.