Palaeopleurosaurus

Palaeopleurosaurus is an extinct genus of diapsid reptiles belonging to the group Sphenodontia.

Palaeoleurosaurus fossils were discovered in Bavaria, Germany from Toarcian (Early Jurassic) deposits, dated to about 183 million years ago. It is one of the few known aquatic sphenodontians, a lifestyle supported by increased bone density in its gastralia. However, the lack of increase in rib and femur bone density suggests that the lineage of Palaeopleurosaurus became gradually adapted to aquatic lifestyles. Histology shows that the number of growth rings in Palaeopleurosaurus was smaller than the living tuatara, possibly indicating a shorter lifespan.