Psittacosaurus mongoliensis

psittacosaurus skeleton
Psittacosaurus mongoliensis -Osborn, 1923- skeleton
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 in
length,, and mostly bipedal cursors although the forelimbs in these dinosaurs were
relatively long and well-developed.
This bi-pedal dinosaur is thought to
have been a precursor to the horned dinosaurs (ceratopsians), which include
such well-known forms as Triceratops. The name for this dinosaur,
Psittacosaurus, means the 'parrot-lizard' referring to its prominent parrot-like beak.
This beak was one of the principal advances from the
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. In many ways like the construction of its
teeth, it is still very similar to hypsilophodonts.
Psittacosaurus appears to be a link between two large groups of dinosaurs.
Psittacosaurus was one of the most common dinosaurs in the Early Cretaceous collections
from Mongolia. It sometimes makes up over 90% of all the dinosaur bones found.
Psittacosaurus was a plant eater with leaf-shaped
teeth that sliced past one another like the blades of scissors.
It appears to have grabbed plants with its parrotlike beak,
chopped them smaller, and then ground them up with ggastroliths (gizzard stones),
which have been found inside some skeletons of this dinosaur.
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