PBDB Taxon

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Elasmosaurinae

Reptilia - Plesiosauria - Elasmosauridae

Taxonomy

Elasmosaurinae was named as a subfamily. Its type is Elasmosaurus.

It was reranked as the unranked clade Elasmosaurinae by O'Gorman (2019).

It was assigned to Elasmosauridae by Welles (1962); and to Euelasmosaurida by O'Gorman (2019).

Subtaxa

Albertonectes, Elasmosaurus (type genus), Hydrotherosaurus, Nakonanectes, Styxosaurus (syn. Hydralmosaurus), Terminonatator

Synonyms

Styxosaurinae was named by Otero (2016).

It was synonymized subjectively with Elasmosaurinae by O'Gorman (2019).

It was assigned to Elasmosauridae by Otero (2016) and Serratos et al. (2017).

Synonymy list

Year	Name and author
1962	Elasmosaurinae Welles p. 4
2016	Styxosaurinae Otero
2017	Styxosaurinae Serratos et al.
2019	Elasmosaurinae O'Gorman

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967

Rank	Name	Author
—	Cotylosauria	()
—	Amniota
—	Sauropsida
class	Reptilia
subclass	Eureptilia	()
—	Romeriida
—	Diapsida	()
suborder	Sauropterygia
order	Plesiosauria	de Blainville 1835
superfamily	Plesiosauroidea	Welles 1943
family	Elasmosauridae	Cope 1869
—	Euelasmosaurida
—	Elasmosaurinae
—	Elasmosaurinae

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Unr. †Elasmosaurinae

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G. †Albertonectes Kubo et al. 2012

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†Albertonectes vanderveldei Kubo et al. 2012

G. †Hydrotherosaurus Welles 1943

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†Hydrotherosaurus alexandrae Welles 1943

G. †Nakonanectes Serratos et al. 2017

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†Nakonanectes bradti Serratos et al. 2017

G. †Styxosaurus Welles 1943

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†Styxosaurus browni Welles 1952

†Styxosaurus snowii Williston 1890

Invalid names: Alzadasaurus pembertoni Welles and Bump 1949 [synonym]

Invalid names: Hydralmosaurus Welles 1943 [synonym], Thalassonomosaurus marshii Williston 1906 [nomen dubium]

G. †Terminonatator Sato 2003

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†Terminonatator ponteixensis Sato 2003

Invalid names: Styxosaurinae Otero 2016 [synonym]

Diagnosis

Reference	Diagnosis
R. A. Otero 2016 (Styxosaurinae)	Clade of Campanian elasmosaurids from the Western Interior Seaway, distinguished by the following combination of characters: 60 or more cervical vertebrae (the minimal number of cervical vertebrae is based on the count of AMHN 1495 which has 58 cervical vertebrae and few estimated missing cervical centra); presence of mid cervical centra axially elongated reaching a length between two thirds to twice its width, being as broad as high (``can-shaped'' cervical vertebrae); neck much longer than the trunk; skull less than one tenth the cervical series length; plesiomorphic number of 1719 dorsal vertebrae (see `Discussion').