PSITTACOSAURUS (sie-TACK-oh-SORE-us)

Period: Early Cretaceous

Order, Suborder, Family: Ornithischia, Ceratopsia, Psittacosauridae

Location: Asia (Mongolian People's Republic, People's Republic of China, Siberia)

Length: 6 1/2 feet (2 meters)

Psittacosaurus was one of the smallest and most primitive members of the Ceratopsia. It was found in rock that is thought to be Early Cretaceous (the exact age is not known). Psittacosaurus is the earliest known ceratopsian.

Psittacosaurus was first discovered in Outer Mongolia in 1922. Henry Osborn named the first specimen Psittacosaurus mongoliensis and gave a second specimen the name Protiguanodon mongoliense. Later, paleontologists realized that Protiguanodon and Psittacosaurus were the same animal. Additional Psittacosaurus specimens have since been found in China as well, and a number of species have been added.

This small dinosaur did not look much like its later relatives. It had short arms and long grasping hands, and it walked biped-ally (on two legs). It also had a small head without a neck frill or horns. But like all later ceratopsians, it had a high palate (the bone in roof of the mouth), flared cheek bones, and a deep face with a parrotlike beak. This beak is how it got its name, which means "parrot reptile." Although Psittacosaurus did not have a neck frill, it had a small, shelflike edge on the back of its skull. This may have been the beginning of a frill. Psittacosaurus had no horns or large frill for protection; it probably escaped predators by running quickly.

Although the skull of Psittacosaurus, shares many features with later ceratopsians, its skeleton looks like the bipedal ornithischian dinosaurs, such as Fabrosaurus or Hypsilophodon. Osborn at first thought Psittacosaurus was an ornithopod dinosaur. If the skeleton had been found without the skull, we would not know that it was a ceratopsian.

Two of the specimens of Psittacosaurus were tiny juveniles; they are among the smallest known dinosaurs. These juveniles were smaller than a robin. One tiny, nearly perfectly preserved skull is only about an inch long and would fit into a teaspoon. The teeth of the small Psittacosaurus specimens were slightly worn, which means they had already been feeding on tough plant material. A newly hatched Psittacosaurus would have been even smaller.

Psittacosaurus is the only known member of the family Psittacosauridae. Its closest relatives were the protoceratopsid dinosaurs Protoceratops, Bagaceratops, Microceratops, Montanaceratops, and Leptoceratops. Although it is the earliest and most primitive ceratopsian, it is not known if Psittacosaurus was the direct ancestor of the protoceratopsians.