PBDB Taxon

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Seeleyosaurus guilelmiimperatoris

Reptilia - Plesiosauria - Microcleididae

Taxonomy

Plesiosaurus guilelmiimperatoris was named by Dames (1895). Its type specimen is MB.R.1992, a skeleton, and it is a 3D body fossil. Its type locality is Hauff slate quarry, Holzmaden, epsilon II/4, SMNS, which is in a Falciferum marine shale in the Posidonia Shale Formation of Germany.

It was recombined as Seeleyosaurus guilelmiimperatoris by Grossmann (2007) and Benson et al. (2012).

Synonyms

Seeleyosaurus holzmadensis was named by White (1940). Its type specimen is SMNS 12039, a skeleton, and it is a 3D body fossil. Its type locality is Holzmaden, epsilon II/4, non-specific collection data, which is in a Falciferum marine horizon in the Posidonia Shale Formation of Germany.

It was synonymized subjectively with Plesiosaurus guilelmiimperatoris by Persson (1963) and Storrs (1997); it was synonymized subjectively with Seeleyosaurus guilelmiimperatoris by Grossmann (2007).

Synonymy list

Year	Name and author
1895	Plesiosaurus guilelmiimperatoris Dames p. 16 figs. Plates 1-3
1910	Plesiosaurus guilelmiimperatoris Fraas p. 106 figs. Figs 1-5; Plates 6, 7; Plate 10, fig. 6
1940	Seeleyosaurus holzmadensis White p. 461
1963	Plesiosaurus guilelmiimperatoris Persson p. 20
1997	Plesiosaurus guilelmiimperatoris Storrs p. 179
2001	Plesiosaurus guilelmiimperatoris O'Keefe p. 11
2007	Seeleyosaurus guilelmiimperatoris Grossmann pp. 545-546 figs. 2-6
2012	Seeleyosaurus guilelmiimperatoris Benson et al.

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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	Plesiosauroidea	Welles 1943
family	Microcleididae
genus	Seeleyosaurus
species	guilelmiimperatoris	()

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.

†Seeleyosaurus guilelmiimperatoris Dames 1895

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Invalid names: Seeleyosaurus holzmadensis White 1940 [synonym]

Diagnosis

Reference	Diagnosis
F. Grossmann 2007	Moderate-sized plesiosauroid, adults up to 3Æ5 m in length with a skull length of c. 170 mm, temporal openings approximately the same size as the orbits; five premaxillary teeth, a maximum of 20 maxillary teeth, smaller teeth directly around the premaxillary-maxillary suture and 4–5 enlarged teeth in both premaxilla and maxilla near the premaxillary-maxillary suture; teeth with fine striae on the lingual side and distinctly less pronounced or absent striae on the buccal side; maxilla with a long posteroventral process reaching approximately to the middle of the jugal; small parietal foramen situated at the frontal-parietal suture; parasphenoid of oblong form without cultriform process and anterior interpterygoid vacuity with rounded posterior margin; straight pterygoid-ectopterygoid suture; four proximal carpals and tarsals; maximum number of phalanges more than ten in the third digit; limbs long, c. 25 per cent of the overall body length in adults.