''Pleurosaurus'' (meaning "side lizard") is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

diapsid Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The group first appeared about three hundred million years ago ...

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

s belonging to the group Sphenodontia, extinct relatives of the modern

tuatara Tuatara (''Sphenodon punctatus'') are reptiles endemic to New Zealand. Despite their close resemblance to lizards, they are part of a distinct lineage, the order Rhynchocephalia. The name ''tuatara'' is derived from the Māori language and m ...

. ''Pleurosaurus'' fossils were discovered in the Solnhofen Limestone of

Bavaria Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total lan ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

and

Canjuers Canjuers is a calcareous plateau and a military camp in Provence located in southeastern France. It’s the largest military camp in Continental Europe. Geography Situated in the ''département'' of the Var in the Prealps of Castellane, on the sou ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

. It contains two species, ''P. goldfussi'' and ''P. ginsburgi''.Dupret, V. (2004). The pleurosaurs: anatomy and phylogeny. ''Revue de Paléobiologie'', 9: 61-8

/ref> ''Pleurosaurus'' is one of the few known aquatic animal, aquatic sphenodontians. Its body was approximately long, and elongated for

hydrodynamic In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) and ...

streamlining, with comparatively short limbs and a powerful tail. The body was heavily modified from those of other rhynchocephalians, including an elongated triangular skull. It swam via the use of poorly efficient axial undulatory

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 ...

(the movement of the body side to side) in shallow marine environments, and was probably

piscivorous A piscivore () is a carnivorous animal that eats primarily fish. The name ''piscivore'' is derived . Piscivore is equivalent to the Greek-derived word ichthyophage, both of which mean "fish eater". Fish were the diet of early tetrapod evoluti ...

. It had only small limbs, which probably did not aid in swimming, and nostrils placed far back on the head, close to the eyes.

History of discovery

''Pleurosaurus'' was first described from the Solnhofen Limestone by

Christian Erich Hermann von Meyer Christian Erich Hermann von Meyer (3 September 1801 – 2 April 1869), known as Hermann von Meyer, was a German palaeontologist. He was awarded the 1858 Wollaston medal by the Geological Society of London. Life He was born at Frankfurt am Ma ...

in 1834, based on the species ''Pleurosaurus goldfussi.'' In 1970 fossils were reported from the lithographic limestones in a quarry near the village of

Aiguines Aiguines (; oc, Aiguina) is a commune in the Var department in the Provence-Alpes-Côte d'Azur region in southeastern France. Geography Climate Aiguines has a hot-summer Mediterranean climate (Köppen climate classification ''Csa'') closely bo ...

in the

plateau, France. In 1974, ''Pleurosaurus ginsburgi'' was described based on MNHN 1983-4-CNJ 67, a mostly complete skeleton found at the Aiguines quarry.

Description

''Pleurosaurus goldfussi'' and ''Pleurosaurus ginsburgi'' are distinguished by differing skull proportions, different numbers of presacral vertebrae, and considerably shorter forelimbs on ''P. ginsburgi.'' Pleurosaurus dorsal

File:Pleurosaurus 783534.jpg File:Pleurosaurus goldfussi 678e.jpg, ''P. goldfussi'' File:Pleurosaurus goldfussi.JPG, ''P. goldfussi'' File:Pleurosaurus ginsburgi 6578.jpg, ''P. ginsburgi''

References

Jurassic lepidosaurs Sphenodontia Solnhofen fauna Prehistoric reptile genera {{paleo-reptile-stub