PBDB Taxon

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Thalassiodracon

Reptilia - Plesiosauria - Pliosauridae

Taxonomy

Thalassiodracon was named by Storrs and Taylor (1996).

It was assigned to Pliosauroidea by Storrs and Taylor (1996); to Plesiosauria by O'Keefe (2001); to Plesiosauroidea by Ketchum and Benson (2010); to Plesiosauria by Otero et al. (2012); and to Pliosauridae by Ketchum and Benson (2011), Benson et al. (2012) and Benson and Druckenmiller (2014).

Species

Plesiosaurus hexatarsostinus, Plesiosaurus pentetarsostinus, Plesiosaurus triatarsostinus, T. hawkinsii (syn. Plesiosaurus etheridgei, Plesiosaurus etheridgii, Plesiosaurus eleutheraxon)

Synonyms

Plesiosaurus pentetarsostinus was named by Hawkins (1834). Its type specimen is BMNH 2020* [14551], a skeleton (almost complete skeleton), and it is a 3D body fossil.

It was synonymized subjectively with Plesiosaurus hawkinsi by Delair (1960); it was considered a nomen oblitum by Benson et al. (2011).
Plesiosaurus hexatarsostinus was named by Hawkins (1840). Its type specimen is BMNH 2022* [14549], a skeleton (nearly complete skeleton), and it is a 3D body fossil.

It was synonymized subjectively with Plesiosaurus hawkinsi by Delair (1960); it was considered a nomen oblitum by Benson et al. (2011).

Synonymy list

Year	Name and author
1834	Plesiosaurus pentetarsostinus Hawkins p. 40
1840	Plesiosaurus pentatarsostinus Hawkins p. 23
1840	Plesiosaurus hexatarsostinus Hawkins p. 24 figs. Pl. XXVIII
1996	Thalassiodracon Storrs and Taylor
2001	Thalassiodracon O'Keefe p. 10
2010	Thalassiodracon Ketchum and Benson p. 15
2011	Thalassiodracon Ketchum and Benson p. 126
2012	Thalassiodracon Benson et al. fig. 4
2012	Thalassiodracon Otero et al.
2014	Thalassiodracon Benson and Druckenmiller figs. 2-3

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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

Rank	Name	Author
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
—	Sauropsida
class	Reptilia
subclass	Eureptilia	()
—	Romeriida
—	Diapsida	()
suborder	Sauropterygia
order	Plesiosauria	de Blainville 1835
superfamily	Pliosauroidea	Welles 1943
family	Pliosauridae	Seeley 1874
genus	Thalassiodracon	Storrs and Taylor 1996

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.

G. †Thalassiodracon Storrs and Taylor 1996

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†Thalassiodracon hawkinsii Owen 1840

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Invalid names: Plesiosaurus eleutheraxon Seeley 1865 [synonym], Plesiosaurus etheridgei Huxley 1858 [synonym], Plesiosaurus etheridgii Huxley 1858 [synonym]

Invalid names: Plesiosaurus hexatarsostinus Hawkins 1840 [nomen oblitum], Plesiosaurus pentetarsostinus Hawkins 1834 [nomen oblitum], Plesiosaurus triatarsostinus Hawkins 1834 [nomen oblitum]

Diagnosis

Reference	Diagnosis
G. W. Storrs and M. A. Taylor 1996	Small plesiosaur rarely up to 2 meters in length, differing from other genera by its small head; short, pointed rostrum; spatulate mandibular symphysis; neck of moderate relative length; simple propodials lacking massive distal expansions; humerus relatively straight; elongate ischium, hindlimbs slightly longer than forelimbs in adult.