(Thick rib lizard).
Named By: Broili - 1927.
Classification: Chordata, Reptilia, Sauropterygia, Nothosauroidea, Pachypleurosauria.
Species: P. edwardsi (type), P. staubi.
Size: About 1 meter long.
Known locations: Italy - Calcare di Meride Formation and Switzerland - Meride Formation.
Time period: Ladinian of the Triassic.
Fossil representation: Few individuals.
type genus of the Pachypleurosauria, Pachypleurosaurus
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.
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.