Named By: Carrol - 1981.
Classification: Chordata, Sauropsida, Eosuchia.
Species: T. colcanapi (type).
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.
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.
- 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.