Therizinosaurus
Name:
Therizinosaurus
(Scythe lizard).
Phonetic: Ther-ih-zine-oh-sore-us.
Named By: Evgeny Maleev - 1954.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Therizinosauridae.
Species: T. cheloniformis (type).
Type: Probably herbivorous.
Size: Approximately 10 meters long.
Known locations: Mongolia.
Time period: Campanian of the Cretaceous.
Fossil representation: Usually the large hand
claws, and some post cranial remains. Skull unknown.
What
makes Therizinosaurus and others from its group
stand out from other
dinosaurs are the huge claws that are on the end of its fingers. In
Therizinosaurus these claws reached up to one meter
long, and there
purpose has three main theories. The first is for display, with the
larger claws being indicative of reproductive maturity. The second
theory which leads on from the first is for inter species combat
between two males, in a similar manner that ceratopsian
dinosaurs are
thought to have used their horns in dominance combat. This could also
mean Therizinosaurus using its claws against
predatory dinosaurs in
self-defence.
The
third theory is that the claws were aids in reaching up into the tree
canopy to pull down choice pieces of vegetation, in the same kind of
way that a modern day sloth will also use its long claws to reach its
food. This might also imply that Therizinosaurus,
among others of
its group, preferred some plants over others and was more selective
in its feeding. It should also be considered that while one answer
may be more correct, the claws may have also been used for different
purposes depending upon the situation.
Unfortunately,
apart from the claws, only scant partial remains of the rest of the
skeleton are known. This meant that for a long time the exact
morphology was largely unknown, with very early depictions making
Therizinosaurus a predator that used its claws to
take down prey. The
discovery of more similar dinosaurs towards the end of the twentieth
century allowed for the gaps to be filled in, with modern
reconstructions of Therizinosaurus being considered
more accurate.
Members
of this group are thought to be descended from carnivorous
ancestors, but the exact diet of Therizinosaurus
is still not
absolutely certain because the skull is unknown. Without this it is
impossible to look at the dentition and bite characteristics which are
required to learn about an animal’s diet. Other dinosaurs of the
Therizinosauridae,
were certainly herbivorous, but because
carnivores were their immediate known ancestors, it is often
speculated that meat may have still formed part of their diet making
them omnivorous.
Therizinosaurus
is usually depicted with the standard featherless body of old dinosaur
depictions, but sometimes it is also given feathers. It must be
remembered that there is no direct evidence to support the existence of
feathers on Therizinosaurus. Evidence for
feathers mainly comes from
the remains of Beipiaosaurus,
but at a little over two meters in
length, it is one of the smallest members of the group. In contrast
Therizinosaurus is one of the largest, and
creatures of its size
usually have very little if any form of insulation on the grounds of
gigantothermy.
Further reading
- New turtle−like reptile in Mongolia (Russian) - Priroda, 1954(3):
106–108. - Evgeny A. Maleev - 1954.
- On the gigantic claws of mysterious Mesozoic reptiles. -
Paleontologischeskii Zhurnal, 1970(1): 131-141. - A. K. Rozhdestvensky
- 1970.
- Giant claws of Enigmatic Mesozoic Reptiles. - Paleontology Journal,
4(1): 117-125. - A. K. Rozhdestvensky - 1970.
- New data on Therizinosaurus (Therizinosauridae,
Theropoda)
(Russian)." In Dev�tkin, E.V. and N.M. �novska� (eds.), Paleontologi� i
biostratigrafi� Mongolii. Trudy, Sovmestna� Sovetsko−Mongol’ska�
paleontologičeska� kspedici�, 3: 76–92. - Rinchen Barsbold - 1976.
- On a new finding of the hindlimb of Therizinosaurus
sp. from the Late
Cretaceous of Mongolia - Problems on the Geology of Mongolia, 5: 94–98
- A. Perle - 1982.
- A taxonomic and phylogenetic re-evaluation of Therizinosauria
(Dinosauria: Maniraptora) - Journal of Systematic Palaeontology 8 (4):
503–543. - Lindsay E. Zanno - 2010.
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