In Depth
The type genus of the Pachypleurosauria, Pachypleurosaurus would have been a relative of the more famous nothosaurs, yet still be distinct enough to not be classed as a nothosaurine. It should be remembered however that both nothosaurines and pachypleurosaurines are still both classified as nothosauroids due to their physical similarities.
The name Pachypleurosaurus means ‘thick rib lizard’, and is a reference to the thickness of the rib. Such thick ribs are uncommon in terrestrial animals, but in aquatic animals they are quite common since the greater weight helps the animal to stay under the water, rather than just bob about upon the surface. Despite this buoyancy adaptation however, Pachypleurosaurus still retained limbs and feet that would have been useful on the land. This indicates that like their nothosaurine relatives, Pachypleurosaurus would still rest on the shore when not actually hunting in the sea.
Further Reading
Les reptiles du Trias moyen du Monte San Giorgio, Tessin [The reptiles from the Middle Triassic of Monte San Giorgio, Tessino] - A. Toroni - 1979. - On two new specimens of Pachypleurosaurus (Reptilia: Nothosauria) - N. J. Mateer - 1976.
