Psittacosaurus avait des plumes
A recent discovery in China features an extraordinarily well preserved horned Psittacosaurus dinosaur from the early Cretaceous with skin covering much of its skeleton. Large parts of the skin are preserved as a thin dark layer, where the skin has been transformed into a dark carbonized matter.
The most unusual feature, and the reason for the excitement among paleontologists about this fossil, is the presence of about 100 large bristle-like structures on the tail. These structures are restricted to a 10 inch (24cm) long stripe along the top part of the tail, over 14-15 of the tail vertebrae. When they are examined under ultraviolet light they show the same fluorescence as the preserved scales of the skin. This indicates that they might have been keratinized - this means the bristles were most likely made out of the same material that makes up your fingernails.
Over the millions of years that this little dinosaur was buried, sediments built up on top of this specimen to a great depth. This exposed it to many tons of pressure, causing what is called lateral compression, or in more common terms, it was squished flat. This means the bristles were also completely flattened over the time of burial, but we assume that they were originally cylindrical and possibly tubular.
Most bristles exhibit a dark stripe along at least a part of their midline, which possibly indicates the presence of a hollow tube inside these structures, as in the feather-like structures of some theropods. The bristles extend under this skin layer and nowhere lie above it, which indicates that they were attached to the top middle part of the tail only, right above the tail vertebrae.
What exactly these bristles were used for is a complete mystery. Scientists can only speculate since there are no other fossils or existing animals with this feature. They might have been used in display behavior and especially if it is assumed that they were colored. They may have been used to send signals to other psittacosaurs.
Many of the better known ceratopsian dinosaurs had a complex social behavior, which would give some support to the assumption of a display function of the tail ?bristles? in Psittacosaurus. At the shoulder of this specimen the skin structure corresponds well to that seen in skin impressions of the more advanced ceratopsian genus Chasmosaurus, in that irregular rows of large, round, and plate-like scales are separated by numerous small, polygonal, and tubercle-like ones.
At the limbs and tail of this unique Psittacosaurus specimen only the small tubercle-like scales are visible. In the area where the stomach would have been, numerous gastroliths can be seen which are also known from other specimens of the herbivorous psittacosaurs. The discovery of bristle-like structures in Psittacosaurus is of great evolutionary significance since it shows that the skin covering of at least some dinosaurs was much more complex than has ever been imagined before.
Jurassic park institute
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