PBDB Taxon

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Geosaurus

Reptilia - Metriorhynchidae

Taxonomy

Geosaurus was named by Cuvier (1824) [Sepkoski's age data: J Kimm K Nc Sepkoski's reference number: 620]. Its type is Dakosaurus maximus. It is the type genus of Geosaurinae, Geosaurini, Geosaurina.

It was assigned to Saurii by Meyer (1845); to Lacertinidae by d'Orbigny (1849); to Mosasauridae by Gervais (1853); to Crocodilia by Sepkoski (2002); to Metriorhynchidae by Carroll (1988), Gasparini and Iturralde-Vinent (2001), Gasparini et al. (2006) and Jouve (2009); to Thalattosuchia by Larsson and Sues (2007) and Bronzati et al. (2012); to Geosaurini by Cau and Fanti (2011), Young et al. (2013), Young et al. (2013) and Young (2013); to Neosuchia by Nascimento and Zaher (2011) and Sertich and O'Connor (2014); to Geosaurinae by Young and Andrade (2009), Young et al. (2010) and Parrilla-Bel and Canudo (2015); and to Geosaurina by Young et al. (2024).

Species

G. giganteus (syn. G. sommerringi, Halilimnosaurus crocodiloides, Mosasaurus bavaricus, Brachytaenius perennis), G. grandis, G. lapparenti, G. medius

Synonyms

Halilimnosaurus was named by Ritgen (1826).

It was synonymized subjectively with Geosaurus by Zittel (1890) and Young et al. (2010).

It was assigned to Halisaurae by Ritgen (1828).
Ltliminosaurus was named by Romer (1966).

It was synonymized subjectively with Geosaurus by Young et al. (2010).

Synonymy list

Year	Name and author
1824	Geosaurus Cuvier
1826	Halilimnosaurus Ritgen p. 331
1828	Halilimnosaurus Ritgen p. 274
1845	Geosaurus Meyer p. 282
1849	Geosaurus d'Orbigny p. 209
1853	Geosaurus Gervais p. 472
1966	Ltliminosaurus Romer
1988	Geosaurus Carroll
2001	Geosaurus Gasparini and Iturralde-Vinent
2002	Geosaurus Sepkoski
2006	Geosaurus Gasparini et al. p. 72
2007	Geosaurus Larsson and Sues
2009	Geosaurus Jouve
2009	Geosaurus Young and Andrade p. 559
2010	Geosaurus Young et al. p. 856
2011	Geosaurus Cau and Fanti p. 558 fig. 6
2011	Geosaurus Nascimento and Zaher
2012	Geosaurus Bronzati et al.
2013	Geosaurus Young fig. 6
2013	Geosaurus Young et al.
2013	Geosaurus Young et al.
2014	Geosaurus Sertich and O'Connor
2015	Geosaurus Parrilla-Bel and Canudo
2024	Geosaurus Young et al. p. 607

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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
—	Cotylosauria	()
—	Amniota
—	Sauropsida
class	Reptilia
subclass	Eureptilia	()
—	Romeriida

Rank	Name	Author
—	Diapsida	()
—	Archosauromorpha	(Huene 1946)
—	Crocopoda
—	Archosauriformes	Gauthier 1986
—	Eucrocopoda
—	Archosauria	()
—	Pseudosuchia	(Zittel 1890)
—	Suchia	Krebs 1974
—	Paracrocodylomorpha
—	Loricata	(Merrem 1820)
—	Crocodylomorpha	()
infraorder	Thalattosuchia	()
—	Neothalattosuchia
superfamily	Metriorhynchoidea	Young et al. 2010
—	Euthalattosuchia
family	Metriorhynchidae	Fitzinger 1843
subfamily	Geosaurinae	Lydekker 1889
tribe	Geosaurini
subtribe	Geosaurina
genus	Geosaurus	Cuvier 1824

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. †Geosaurus Cuvier 1824

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†Geosaurus giganteus Sömmerring 1816

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Invalid names: Brachytaenius perennis Meyer 1842 [synonym], Geosaurus sommerringi Meyer 1831 [synonym], Halilimnosaurus crocodiloides Ritgen 1826 [synonym], Mosasaurus bavaricus Holl 1829 [synonym]

†Geosaurus grandis Wagner 1858

†Geosaurus lapparenti Debelmas and Strannoloubsky 1957

†Geosaurus medius Wagner 1858

Invalid names: Halilimnosaurus Ritgen 1826 [synonym], Ltliminosaurus Romer 1966 [synonym]

Diagnosis

Reference	Diagnosis
M. T. Young and M. B. Andrade 2009	Metriorhynchid thalattosuchian possessing brevirostrine to short mesorostrine snout; strongly lateromedially compressed teeth, with the dental carinae formed by a raised ridge (keel), finely serrated (composed of true denticles); maxillary crowns moderately enlarged; cranial bones smooth, lacking conspicuous ornamentation; prefrontal teardrop-shaped, with the inflexion point directed posteriorly approximately 70° from the anteroposterior axis of the skull; acute angle formed by the lateral and medial processes of the frontal; antorbitol cavity present and much longer than higher; lacrimal–prefrontal fossa present, with a crest along the sutural contact
M. T. Young et al. 2010	Metriorhynchid thalattosuchian with strongly lateromedially compressed teeth, and with a keeled denticulate carinae; the premaxillary, maxillary, and dentary teeth are tri-faceted upon their labial surface; there is a notch at the premaxilla–maxilla contact that an enlarged dentary tooth fits into; upper and lower jaw dentition arranged as opposing blades; cranial bones smooth, lacking conspicuous ornamentation; acute angle formed by the lateral and medial processes of the frontal; surangular poorly developed, terminating caudal to the anterior margin of the orbit; mandibular symphysis terminating prior to the antorbital fossa; robust and well-developed sclerotic ring encompassing the entire orbit.