Drepanosaurus
Name:
Drepanosaurus
(Sickle claw).
Phonetic: Dre-pan-o-sore-us.
Named By: Pinna - 1979.
Classification: Chordata, Reptilia,
Protorosauria, Drepanosauridae.
Species: D. unguicaudatus
(type).
Diet: Insectivore?
Size: Roughly about 45 centimetres.
Known locations: Italy.
Time period: Norian of the Triassic.
Fossil representation: Single individual lacking the
skull.
Drepanosaurus
is the type genus of the Drepanosauridae, a special group of
diapsid
reptiles that are noted for having prehensile tails. What this means
is that the tail could be wrapped around objects for additional grip.
In addition to this there was a hook on the end of the tail that
provided even greater grip. the feet and hands are also formed in
such a way that they could easily grasp around things like branches,
and these features combined have led to the generally accepted opinion
that Drepanosaurus were arboreal in nature. This
means that rather
than run around on the ground, a Drepanosaurus
would have spent its
life climbing along the branches of trees. To further the climbing
hypothesis, the skeletal structure of Drepanosaurus,
particularly
the limbs is very robust with attachment points for strong muscles that
would have easily provided the strength for a Drepanosaurus
to pull
itself up a vertical surface.
One
feature that really makes Drepanosaurus stand out
from its relatives is
the enlarged claw that grew out from the end of the second digit. So
large was this claw that it was almost the same size as the rest of the
actual hand. This claw might have been used for two reasons. One is
that Drepanosaurus was quite large when compared to
its other
relatives; in fact the holotype skeleton of Drepanosaurus
is more
than double the length of its slightly more famous relative,
Megalancosaurus.
This would mean a greater weight and greater need
for grip when climbing through the trees, but this reason does not
satisfactorily explain the shape of the claw which is very thick and
strongly curved. An alternative explanation is that the claw was used
more for lifting up bark and digging into crevices and grooves on trees
so that small invertebrates such as grubs could be reached and consumed.
Further reading
- Drepanosaurus unguicaudatus, nuovo genere e
nuova specie di
Lepidosauro del trias alpino [New genus and new species of Triassic
Alpine Lepidosaur]. - atti Soc. It. Sc.Nat. 121:181-192.
- G. Pinna - 1980.
- On Drepanosaurus unguicaudatus, an upper
Triassic lepidosaurian
from the Italian Alps. - Journal of Paleontology
50(5):1127-1132. - G. Pinna - 1986.
- The shoulder girdle and anterior limb of Drepanosaurus
unguicaudatus (Reptilia, Neodiapsida) from the upper
Triassic
(Norian of Northern Italy. - Zoological Journal of the Linnean
Society 111(3):247-264 - S. Renesto - 1994.
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