Claudiosaurus

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Claudiosaurus is an extinct, small reptile from Madagascar that lived about 259 to 252 million years ago, during the Late Permian. It probably lived in wetlands and may have spent a lot of time in the water, though it could also walk on land.

What Claudiosaurus looked like
- It was about 60 centimeters long (around 2 feet).
- It had a relatively long neck and a small head.
- Its body had 16 trunk vertebrae and it carried bones called gastralia on its underside.
- The tail was long, with more than 45 vertebrae.
- Its jaws had many small teeth, and the roof of the mouth had many tiny denticles.
- The sternum (breastbone) was not yet solid bone (unossified).
- Some bones were thickened (pachyostosis), which may have helped with living in water.
- The pectoral girdle (shoulder area) was similar to other early diapsid reptiles.

Ecology and behavior
Claudiosaurus is thought to have been amphibious, using its limbs to move through water but able to walk on land as well. It may have fed on small invertebrates, such as crustaceans.

Classification
When first described, Claudiosaurus was sometimes placed with sauropterygians (the group that includes plesiosaurs). Later researchers have often classified it as a basal neodiapsid (an early member of the diapsid reptiles), and some studies link it with Acerosodontosaurus. There is ongoing debate about exactly where Claudiosaurus fits in the reptile family tree; a few later works argued it is not a stem-turtle.

Paleoenvironment
The rocks where Claudiosaurus was found come from the Lower Sakamena Formation in Madagascar, a wetland-like environment inside a rift valley. The climate was temperate, warm, and humid with seasonal rains. Plants from the area included Glossopteris and other ancient flora. Other animals known from the same rocks include various early reptiles, fish, and temnospondyls, giving a picture of a diverse wetland ecosystem.

Type species and specimen
The type species is Claudiosaurus germaini, named after Claude Germain. A well-known specimen is displayed at the Redpath Museum in Montreal.

Origin of the name
Claudiosaurus combines Claude (for Claude Germain) with saurus, meaning lizard.