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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