Psittacosaurus (meaning “parrot lizard”) was a small, very primitive ceratopsian. This fast-moving plant-eater had a narrow, horny beak with no teeth, and cheek teeth towards the rear of the mouth. It had a boxy skull with short, horn-like projections on the cheeks. It had four long fingers on each hand; the arms were much shorter than the legs. Psittacosaurus was from about 2.6 to 6.5 feet (80 cm to 2 m) long and weighed about 50-175 pounds (25-80 kg). They were roughly 4 feet (1.2 m) tall. The growth lines in Psittacosaurus mongoliensis bones (similar to studying tree rings to deduce a tree’s age) have led paleontologists to think that it had a life span of at least 10-11 years. Psittacosaurus lived during the early Cretaceous period, about 119-97.5 million years ago. Psittacosaurus may have been a herding animal, like some other ceratopsians. Psittacosaurus was a ceratopsian, whose intelligence (as measured by its relative brain to body weight, or EQ) was intermediate among the dinosaurs. Psittacosaurus could walk on two or four legs. Its arms were substantially shorter than its legs. It may have been a fast runner. This was its primary means of escaping predators. Fossils of Psittacosaurus have been found in Mongolia, China, and Thailand. It was named by paleontologist Henry F. Osborn in 1923. Psittacosaurus was an ornithischian dinosaur, the order of bird-hipped, herbivorous dinosaurs. It was a very early ceratopsian (beaked, herding herbivores, that include Protoceratops, Triceratops, Styracosaurus, etc.), and a Protoceratopsid (an early ceratopsian, which included Montanoceratops, Leptoceratops, and others). The type species is Psittacosaurus mongoliensis (Osborn, 1923). There are many other species of Psittacosaurus, including P. mazongshanensis (Xu, 1997), P. meileyingensis (Sereno, Chao, Cheng, and Rao, 1988), P. neimongoliensis (D. A. Russell and Zhao, 1996), P. ordosensis (D. A. Russell, and Zhao, 1996), P. sattayaraki (Buffetaut and Suteethorn, 1992), P. sinensis (Young, 1958), and P. xinjiangensis (P. Sereno and Chao, 1988).