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

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), 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 J ...

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 disco ...

,'' 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 Toarcian ...

)

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 ''Pleurosaurus'' (meaning "side lizard") is an extinct genus of diapsid reptiles belonging to the group Sphenodontia, extinct relatives of the modern tuatara. ''Pleurosaurus'' fossils were discovered in the Solnhofen Limestone of Bavaria, Germ ...

'' 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 Fish locomotion is the various types of animal locomotion used by fish, principally by swimming. This is achieved in different groups of fish by a variety of mechanisms of propulsion, most often by wave-like lateral flexions of the fish's body a ...

.Dupret, V. (2004). The pleurosaurs: anatomy and phylogeny. ''Revue de Paléobiologie'', 9: 61-8

/ref> ''

Vadasaurus ''Vadasaurus'' is an Extinction, extinct genus of rhynchocephalian closely related to the aquatic pleurosauridae, pleurosaurids. Although this genus was not as specialized as the eel-like pleurosaurs for aquatic life, various skeletal features su ...

'' and ''

Derasmosaurus ''Derasmosaurus'' is an extinct species of rhynchocephalian known from the Pietraroja Plattenkalk of Italy. It was originally considered to be a specimen of ''Lacerta brevicauda'' by Costa in 1866, it was later considered a specimen of the l ...

'' 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