''Ceresiosaurus'' 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 ...

aquatic

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 ...

of lariosaurine

nothosaurid Nothosauridae are an extinct family of carnivorous aquatic sauropterygian reptiles from the Triassic time period of China, France, Germany, Israel, Italy, Netherlands, Russia, Switzerland, and northern Africa. Phylogeny The cladogram shown bel ...

sauropterygia 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 ...

n 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 ...

(

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 ...

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). ...

boundary) 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 ...

, southern

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 northern

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...

. Ceresiosaurus, meaning "Lizard of

Ceresio __NOTOC__ Lake Lugano ( it, Lago di Lugano or , from la, Ceresius lacus; lmo, Lagh de Lugan) is a glacial lake which is situated on the border between southern Switzerland and northern Italy. The lake, named after the city of Lugano, is situated ...

" (Ceresio is the name of the

Lake Lugano __NOTOC__ Lake Lugano ( it, Lago di Lugano or , from la, Ceresius lacus; lmo, Lagh de Lugan) is a glacial lake which is situated on the border between southern Switzerland and northern Italy. The lake, named after the city of Lugano, is situated ...

, in

). 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 ...

, ''Ceresiosaurus calcagnii'', was named by

Bernhard Peyer Bernhard Peyer (25 July 1885 – 23 February 1963) was a Swiss paleontologist and anatomist who served as a professor at the University of Zurich. A major contribution was on the evolution of vertebrate teeth. Peyer was born in Schaffhausen, Switze ...

1931 Events January * January 2 – South Dakota native Ernest Lawrence invents the cyclotron, used to accelerate particles to study nuclear physics. * January 4 – German pilot Elly Beinhorn begins her flight to Africa. * January 22 – Sir I ...

. ''C. calcagnii'' is known from both the Cava superiore and Cava inferiore beds of the Lower Meride Limestone at Monte San Giorgio, dating to the latest Anisian of the Middle Triassic. Rieppel (1998) suggested that the back then

monospecific In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus ''Ceresiosaurus'', is a

junior synonym The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...

of the better known ''

Lariosaurus ''Lariosaurus'' is an extinct genus of nothosaurid from the Middle Triassic (late Anisian to late Ladinian stage) of central and western Europe and China. With a length of just , it was one of the smallest known nothosaurs. First discovered at Pe ...

'', yet he kept it type species as a separate species under the new combination ''L. calcagnii''. In 2004, however, this synonymy was objected by Hänni who described and name a second species of ''Ceresiosaurus'', ''C. lanzi'' - a separation supported by several other authors since. This species is known only from the

stratigraphically Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostrati ...

younger Cassima beds of Monte San Giorgio, although also from the Lower Meride Limestone, dating to possibly the lowest

age. The species in a subtropical

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...

al environment with varying open marine influences, and alongside many related but smaller species of

s and

pachypleurosaurid 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 , ...

s. ''Ceresiosaurus'' represents one of the largest vertebrate of up to snout-tail length from the very diversified paleoenvironment of the Middle Triassic Monte San Giorgio.

Palaeobiology

''Ceresiosaurus'' was much more elongated than its relatives, reaching in length, and had fully developed flippers with no trace of visible toes. It had multiple elongated

phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...

, making the flippers much longer than in most other nothosaurs, and more closely resembling those of the later

plesiosaur The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared ...

s. ''Ceresiosaurus'' also had the shortest

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

of any known nothosaur, which further increased its resemblance to plesiosaurs. Although possessing a long neck and tail, ''Ceresiosaurus'' may not have swum by undulating its body. Analysis of the bone structure of the hips and powerful tail suggest that it instead propelled itself through the water much like a

penguin Penguins (order (biology), order List of Sphenisciformes by population, Sphenisciformes , family (biology), family Spheniscidae ) are a group of Water bird, aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: on ...

. The evidence of

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 in the preserved stomach of ''Ceresiosaurus'' remains lend credence to the theory of it being a fast swimmer.

References

External links

Palaeos.com
Nothosaurs Triassic sauropterygians Middle Triassic reptiles of Europe Anisian life Sauropterygian genera {{Triassic-reptile-stub