''Serpianosaurus'' 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 ...

pachypleurosaur left, 220px, '' Pachypleurosaurus'' Pachypleurosauria is an extinct clade of primitive sauropterygian reptiles that vaguely resembled aquatic lizards, and were limited to the Triassic period. They were elongate animals, ranging in size from , w ...

s known from the

Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma and ...

(late

Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic Ep ...

and early

Ladinian The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between Ma and ~237 Ma (million years ago). The Ladinian was preceded by the Anisian and succeeded by the Carnian (part of the Upper or Late Triassic). ...

stages) deposits of

Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...

and

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 ...

. It was a small reptile, with the type specimen of ''S. mirigiolensis'' measuring long. Serpianosaurus mirigolensis img 4452

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s of the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

, '' S. mirigolensis'', have been found from the middle

Grenzbitumenzone The Besano Formation is a geological formation in the southern Alps of northwestern Italy and southern Switzerland. This formation, a short but fossiliferous succession of dolomite and black shale, is famous for its preservation of Middle Triassic ...

, the oldest strata of

Monte San Giorgio Monte San Giorgio is a mountain and UNESCO World Heritage Site on the border between Switzerland and Italy. It is part of the Lugano Prealps, overlooking Lake Lugano in the Swiss Canton of Ticino. Monte San Giorgio is a wooded mountain, rising ...

, an area well known for its abundant pachypleurosaur remains. ''Serpianosaurus'' in the Paleobiology Database
/ref> The locality dates back to sometime around the

boundary of the

, around 242 Ma, with ''Serpianosaurus'' most likely occurring strictly during the latest Anisian. This makes it the one of the oldest

sauropterygians Sauropterygia ("lizard flippers") is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria became ...

from Monte San Giorgio, with only the rare pachypleurosaur ''

Odoiporosaurus ''Odoiporosaurus'' is an extinct genus of pachypleurosaur known from the Middle Triassic (middle Anisian stage) Besano Formation (Grenzbitumenzone) of northern Italy. It contains a single species, ''Odoiporosaurus teruzzii''. ''Odoiporosauru ...

'' being older. Certain aspects of its morphology also suggest it is one of the most basal forms. Cajus G. Diedrich in

2013 File:2013 Events Collage V2.png, From left, clockwise: Edward Snowden becomes internationally famous for leaking classified NSA wiretapping information; Typhoon Haiyan kills over 6,000 in the Philippines and Southeast Asia; The Dhaka garment fact ...

described and named a second species, ''S. germanicus'', based on a

postcranial Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...

skeleton A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...

and various additional isolated remains from the

Karlstadt Formation Karlstadt may refer to: * Karlstadt am Main, Germany * Karlovac, Croatia (German name Karlstadt) * Karlstad, Sweden * Karlstad, Minnesota People with the surname * Andreas Karlstadt, contemporary of Martin Luther during the Reformation See also ...

of Germany. This species represents the oldest well known record of this genus, as it comes from the upper Pelsonian, dating to the late

stage of the Middle Triassic. The genus can be distinguished from other closely related pachypleurosaurs on the basis of its proportionally large skull and straight jaw. Like many other pachypleurosaurs,

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

can be seen in ''Serpianosaurus''. Males and females are thought to differ in

humeral The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a round ...

size and shape. Any

pachyostosis Pachyostosis is a non-pathological condition in vertebrate animals in which the bones experience a thickening, generally caused by extra layers of lamellar bone. It often occurs together with bone densification (osteosclerosis), reducing inner ca ...

of the

ribs The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels. The sternum, together known as the thoracic cage, is a semi- ...

is absent in ''Serpianosaurus'' specimens.Rieppel, O. (1989). A New Pachypleurosaur (Reptilia: Sauropterygia) from the Middle Triassic of Monte San Giorgio, Switzerland. ''Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences'' 323(1212):1-73. It is closely related to the genus ''

Neusticosaurus ''Neusticosaurus'' (sometimes misspelled ''Neuticosaurus'') ("swimming lizard"), is an extinct genus of marine reptile belonging to the pachypleurosaurs, from Italy, Switzerland and Germany. ''Neusticosaurus'' was one of the smallest nothosaur ...

''.Palaeos
/ref>

References

Pachypleurosaurs Anisian life Triassic sauropterygians Middle Triassic reptiles of Europe Triassic Germany Triassic Switzerland Fossils of Germany Fossils of Switzerland Fossil taxa described in 1989 Fossil taxa described in 2013 Sauropterygian genera {{triassic-reptile-stub