Pleurosauridae is an extinct family of sphenodontian reptiles, known from the

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

of Europe. Members of the family had long-snake like bodies with reduced limbs that were adapted for aquatic life in marine environments. It contains two genera, ''

Palaeopleurosaurus ''Palaeopleurosaurus'' is an extinct genus of diapsid reptiles belonging to the group Sphenodontia.Dupret, V. (2004). The pleurosaurs: anatomy and phylogeny. ''Revue de Paléobiologie'', 9: 61-8/ref> ''Palaeopleurosaurus'' fossils were dis ...

,'' which is known from the

Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...

(

Toarcian The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 182.7 Ma (million years ago) and 174.1 Ma. It follows the Pliensbachian and is followed by the Aalenian. The Toar ...

)

Posidonia Shale The Posidonia Shale (german: Posidonienschiefer, also called Schistes Bitumineux in Luxembourg) geologically known as the Sachrang Formation, is an Early Jurassic (Toarcian) geological formation of southwestern and northeast Germany, northern Swit ...

of Germany, as well as '' Pleurosaurus'' from the Late Jurassic of Germany and France. ''Paleopleurosaurus'' is more primitive than the later ''Pleurosaurus'', with a skull similar to those of other sphenodontians, while that of ''Pleurosaurus'' is highly modified relative to other sphendontians. They likely swam via anguilliform locomotion.Dupret, V. (2004). The pleurosaurs: anatomy and phylogeny. ''Revue de Paléobiologie'', 9: 61-8

/ref> '' Vadasaurus'' and '' Derasmosaurus'' from the Late Jurassic and Early Cretaceous of Europe have been placed as part of this family in some studies, but lack the body elongation that typifies the other two genera.

References

Jurassic lepidosaurs Sphenodontia Toarcian first appearances Late Jurassic extinctions Prehistoric reptile families Taxa named by Richard Lydekker {{paleo-reptile-stub