Tuojiangosaurus
Name:
Tuojiangosaurus
(Tuo river lizard).
Phonetic: Too-oh-jang-oh-sore-us.
Named By: Dong et al. - 1977.
Classification: Chordata, Reptilia, Dinosauria,
Ornithischia, Stegosauria, Stegosauridae.
Species: T. multispinus (type).
Diet: Herbivore.
Size: Up to 7 meters long.
Known locations: China, Sichuan Province -
Upper Shaximiao Formation.
Time period: Late Jurassic.
Fossil representation: Remains of two individuals,
one of which is over half complete.
Tuojiangosaurus
was the first stegosaurid
to be discovered in China, and today
remains the best known from Asia. Tuojiangosaurus
itself is seen as a
basal (primitive) form that displays a standard stegosaurid shape
and posture while retaining features that would be lost in later
genera. Tuojiangosaurus seems to have been
limited to a quadrupedal
posture that saw its head held close to the ground where it could feed
upon low vegetation. The teeth of Tuojiangosaurus
are similar to
those of other related dinosaurs and are more suitable for use upon
softer vegetation that did not require a lot of pull to remove from the
main plants.
Tuojiangosaurus
had very distinctive back plates that are tall, narrow and
triangular. These plates run from the neck to about half way down on
the tail, and like most stegosaurids, were at their largest when
over the hips. While early depictions of stegosaurids saw these
plates as being for either defence or thermoregulation, modern
analysis has found the plates to not really be suitable for either
of these purposes. The plates themselves are too weak and brittle to
protect against a powerful bite, and not adapted enough for an
efficient thermoregulation purpose. This leaves the explanation of
inter species display where stegosaurids could recognise others of
their kind by the shape and arrangement of the plates which differed
between individual genera and species.
One
part of Tuojiangosaurus that was almost certainly
for defence against
predators was the spiked tail or ‘thagomizer’ as it is known. The
spikes on Tuojiangosaurus’s thagomizer were
arranged at a forty-five
degree angle, and evidence associated with other stegosaurids
strongly indicates that this was an active weapon for use against
attacking dinosaurs. Whereas the thagomizer spikes of Stegosaurus
were used against predators like Allosaurus,
the thagomizer of
Tuojiangosaurus was likely a defence against similar
predatory theropod
dinosaurs such as Sinraptor.
Further reading
- On the stegosaurian remains from Zigong (Tzekung), Szechuan province.
- Z. Dong, X. Li, S. Zhou & Y. Zhang - 1977.
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