Psittacosaurus mongoliensis Archosauria: Ornithischia: Ceratopsia: Psittacosauridae Locality: Gobi Desert, southern Mongolia Age: Early Cretaceous (Aptian-Albian), 115 million years ago Meaning of name: "parrot lizard" Size: a sheep The ceratopsids are divided into two groups: the Early Cretaceous psittacosaurids, or parrot-beaked dinosaurs, and the Late Cretaceous neoceratopsids, that unites two groups of horned dinosaurs, protoceratopsids and ceratopsids. The psittacosaurids, known only from the late Early Cretaceous of Central Asia, are considered to be close to an ancestor of the horned dinosaurs. Both the parrot-beaked and horned dinosaurs possessed jaws, being curved and tapered foreward and the lateral teeth highly specialized to masticate the vegetative food. Psittacosaurids were relatively small, up to 2 meters long, and mostly bipedal cursors although the forelimbs in these dinosaurs were relatively long and well-developed. This dinosaur, which spent most of its time standing on two legs, is thought to have been near the ancestry of the horned dinosaurs (neoceratopsians), which include such well known forms as Triceratops. The generic name for this dinosaur, Psittacosaurus, means the 'parrot-lizard' in reference to its prominent parrot-like beak. This feature was one of the principal advances of this form from the generalised bipedal fabrosaurids and hypsilophodontids which gave rise to it. Psittacosaurus was the first step on the path towards the four-footed, horned descendants that were to appear more than twenty millions years later. It had a special bone called the rostral, found elsewhere only in the horned dinosaurs, even though in many ways, such as in the construction of its teeth, it is still very similar to hypsilophodonts. In a way, Psittacosaurus is a linking chain between two large groups of dinosaurs! Psittacosaurus was one of the most common dinosaurs in the Early Cretaceous collections from Mongolia-sometimes making up over 90% of all the dinosaur bones found, most frequently in lake and stream deposits. Psittacosaurus was a plant eater with leaf-shaped teeth that sliced past one another like the blades of scissors. It must have grabbed plants with its parrotlike beak, chopped them up, and then smashed them up with gizzard stones, which have been found inside the bodv cavity of some skeletons of this little dinosaur. |
