Name:
Pachypleurosaurus
(Thick rib lizard).
Phonetic: Pak-ee-plur-o-sore-us.
Named By: Broili - 1927.
Classification: Chordata, Reptilia,
Sauropterygia, Nothosauroidea, Pachypleurosauria.
Species: P. edwardsi
(type), P. staubi.
Diet: Carnivore/Piscivore.
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.
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.
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