''Pleurosaurus'', from

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

πλευρά (''pleurá''), meaning "rib" or "side", and σαυρος (''sauros''), meaning "lizard", is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of aquatic

reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...

s belonging to the order

Rhynchocephalia Rhynchocephalia (; ) is an order of lizard-like reptiles that includes only one living species, the tuatara (''Sphenodon punctatus'') of New Zealand. Despite its current lack of diversity, during the Mesozoic rhynchocephalians were a speciose g ...

. ''Pleurosaurus'' fossils have primarily been discovered in the Solnhofen Limestone of

Bavaria Bavaria, officially the Free State of Bavaria, is a States of Germany, state in the southeast of Germany. With an area of , it is the list of German states by area, largest German state by land area, comprising approximately 1/5 of the total l ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

and the Canjuers lagerstatte near Canjuers,

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

, both dating to the

Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...

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

/ref>

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 in Frankfurt am ...

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 (; ) is a rural commune in the Var department in the Provence-Alpes-Côte d'Azur region in Southeastern France. It is located within the arrondissement of Brignoles, 18 km (11.1 mi) southwest of Castellane in neighbouring ...

in the Canjuers plateau, France. In 1974, ''Pleurosaurus ginsburgi'' was described based on MNHN 1983-4-CNJ 67, a mostly complete skeleton found at the Aiguines quarry. ''Pleurosaurus'' is one of two unambiguous members of the family Pleurosauridae, alongside '' Palaeopleurosaurus'' from the Early Jurassic of Germany. In 2012, fragmentary remains likely belonging to ''P. goldfussi'' were reported from central Poland.

Description

''Pleurosaurus'' is one of the few known aquatic sphenodontians. It reached a maximum body length of . The body and especially the tail were elongated, while the limbs were comparatively short. The elongated triangular skull was highly modified from those present in other rhynchocephalians. ''Pleurosaurus'' swam via undulating its tail from side to side ( anguilliform locomotion), while it probably used its limbs to steer. It lived in shallow marine environments, and was probably

piscivorous A piscivore () is a carnivorous animal that primarily eats fish. Fish were the diet of early tetrapod evolution (via water-bound amphibians during the Devonian period); insectivory came next; then in time, the more terrestrially adapted rept ...

. ''Pleurosaurus goldfussi'' and ''Pleurosaurus ginsburgi'' are distinguished by differing skull proportions, different numbers of presacral vertebrae (50 in ''P. goldfussi'' vs 57 in ''P. ginsburgi''), and considerably shorter forelimbs on ''P. ginsburgi.'' File:Pleurosaurus goldfussi 678e.jpg, ''P. goldfussi'' File:Pleurosaurus goldfussi.JPG, ''P. goldfussi'' File:Pleurosaurus ginsburgi 6578.jpg, ''P. ginsburgi''

References

Jurassic lepidosaurs Rhynchocephalia Solnhofen fauna Prehistoric reptile genera Fossil taxa described in 1831 {{paleo-reptile-stub