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''Aristonectes'' (meaning 'best swimmer') is an extinct
Analysis of a specimen from the Lopez de Bertodano Formation indicates that ''Aristonectes'' was one of the largest plesiosaurs ever to exist, with an estimated body length of and body mass of per Paul and per O'Gorman and his colleagues.
''Aristonectes'' was classified variously since its original 1941 description, but a 2003 review of plesiosaurs from Patagonia conducted by Gasparini ''et al.'' (2003) found that ''Aristonectes'' was most closely related to elasmosaurid plesiosaurs like ''Otero ''et al.'' (2014), ''Aristonectes quiriquinensis'', sp. nov., a new highly derived elasmosaurid from the upper Maastrichtian of central Chile
/ref> returned ''Aristonectes'' to Elasmosauridae, recovering the genus as a derived elasmosaurid and therefore relegating Aristonectidae to a subfamily of Elasmosauridae, as Aristonectinae.
Taxonomic history of ''Aristonectes''
{{Taxonbar, from=Q2154474 Late Cretaceous plesiosaurs Maastrichtian life Late Cretaceous reptiles of South America Plesiosaurs of South America Cretaceous Argentina Fossils of Argentina Cañadón Asfalto Basin Cretaceous Chile Fossils of Chile Cretaceous Antarctica Fossils of Antarctica Fossil taxa described in 1941 Sauropterygian genera
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of plesiosaur from the Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...
Paso del Sapo Formation of what is now Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
, the Quiriquina Formation of Chile
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
and the Lopez de Bertodano Formation of Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...
. 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 specime ...
is ''Aristonectes parvidens'', first named by Cabrera in 1941.
Description
Analysis of a specimen from the Lopez de Bertodano Formation indicates that ''Aristonectes'' was one of the largest plesiosaurs ever to exist, with an estimated body length of and body mass of per Paul and per O'Gorman and his colleagues.
Classification
''Aristonectes'' was classified variously since its original 1941 description, but a 2003 review of plesiosaurs from Patagonia conducted by Gasparini ''et al.'' (2003) found that ''Aristonectes'' was most closely related to elasmosaurid plesiosaurs like ''Elasmosaurus
''Elasmosaurus'' (;) is a genus of plesiosaur that lived in North America during the Campanian stage of the Late Cretaceous period, about 80.5million years ago. The first specimen was discovered in 1867 near Fort Wallace, Kansas, US, and was se ...
''. The authors also considered '' Morturneria'' a junior synonym of ''Aristonectes'' because the former's holotype has unfused neural arches of the vertebrae indicative of juvenile status. Subsequent study, however, revalidated ''Morturneria'' based on non-ontogenetic differences from ''Aristonectes''.
''Aristonectes'' was placed within its own family, Aristonectidae, along with '' Tatenectes'', ''Kaiwhekea
''Kaiwhekea'' () is an extinct genus of plesiosaur from the Late Cretaceous (Maastrichtian age) of what is now New Zealand.
History of discovery
The type species, ''Kaiwhekea katiki'', was first described by Arthur Cruickshank and Ewan Fordyc ...
'', and '' Kimmerosaurus'', by O'Keefe and Street (2009), as sister family of the polycotylid cryptoclidoids. However, subsequent studies (Otero ''et al.'', 2014)/ref> returned ''Aristonectes'' to Elasmosauridae, recovering the genus as a derived elasmosaurid and therefore relegating Aristonectidae to a subfamily of Elasmosauridae, as Aristonectinae.
See also
*List of plesiosaur genera
This list of plesiosaurs is a comprehensive listing of all genera that have ever been included in the order Plesiosauria, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considered in ...
* Timeline of plesiosaur research
This timeline of plesiosaur research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, taxonomic revisions, and cultural portrayals of plesiosaurs, an order of marine reptiles that flourished dur ...
Notes
References
External links
Taxonomic history of ''Aristonectes''
{{Taxonbar, from=Q2154474 Late Cretaceous plesiosaurs Maastrichtian life Late Cretaceous reptiles of South America Plesiosaurs of South America Cretaceous Argentina Fossils of Argentina Cañadón Asfalto Basin Cretaceous Chile Fossils of Chile Cretaceous Antarctica Fossils of Antarctica Fossil taxa described in 1941 Sauropterygian genera