Thadeosaurus
Name: Thadeosaurus
(Thadeo's lizard).
Phonetic: Fad-ee-o-dore-us.
Named By: Carrol - 1981.
Classification: Chordata, Sauropsida, Eosuchia.
Species: T. colcanapi (type).
Type: Carnivore/Insectivore/Piscivore?
Size: 60 centimetres long.
Known locations: Madagascar - Lower Sakamena
Formation.
Time period: Wuchiapingian of the Permian.
Fossil representation: Several specimens, but the
skull is only known from a juvenile.
With
a
morphology like we see in lizards today, Thadeosaurus
had a very long
tail making up over half of its total body length. The legs were long
and had long toes terminating in claws. It is likely that as
Thadeosaurus walked, the toes would always be in
contact with the ground. Thadeosaurus
had a well
developed breastbone suggesting attachments for powerful muscles in the
upper body. As well as running, it may have been able to combine
this strength with the claws on its long toes for climbing.
Another
question worth considering though is could Thadeosaurus
have been semi
aquatic? As mentioned, the toes of Thadeosaurus
were very long,
but it does not make much sense for a terrestrial animal to have
dragged its toes across the ground, it would just get slowed down.
So perhaps Thadeosaurus was not the fast running
land predator it
has often been made out to be. If the toes of Thadeosaurus
were
webbed in life however, they would have made very powerful paddles to
push Thadeosaurus through the water. A semi
aquatic lifestyle could
also explain the development of strong chest muscles, pushing through
the water and dense aquatic undergrowth, or perhaps slippery wet
rocks near the edge of the water.
Further
support for a semi aquatic lifestyle for Thadeosaurus
could also come
from close relatives of the genus. These include the Tangasauridae,
a group of diapsid reptiles that show strong development to swimming.
Separate to these the genus Claudiosaurus,
similar to Thadeosaurus,
also shows developments that would help a creature that was at least
semi-aquatic.
Further reading
- Plesiosaur ancestors from the upper Permian of Madagascar. -
Philosophical Transactions of the Royal Society. B. 293 (1066):
315–383. - R. L. Carroll. - 1981.
- Ontogenetic changes in the eosuchian reptile Thadeosaurus.
- Journal
of vertebrate Paleontology vol 4 pp64-84. - Philip J. Currie &
Robert L. Carroll - 1984.
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