Named By: Georges Cuvier - 1824.
Synonyms: Brachytaenius, Halilimnosaurus.
Classification: Chordata, Reptilia, Archosauromorpha, Crurotarsi, Crocodylomorpha, Mesoeucrocodylia, Thalattosuchia, Metriorhynchidae.
Species: G. giganteus (type), G. grandis, G. lapparenti.
Size: Around 3 meters long.
Known locations: France and Germany.
Time period: Tithonian of the Jurassic through to Valanginian of the Cretaceous.
Fossil representation: Multiple specimen
is some confusion regarding Geosaurus
reconstructions as there were
once both long and short snouted forms of the genus. One former
species of Geosaurus in particular known as G.
suevicus was an almost
complete specimen which was commonly used as a base for the majority of
early Geosaurus reconstructions. Later analysis
in 2009 by Mark
T. Young and Marco Brandalise de Andrade however found this fossil to
actually be a specimen of another marine crocodile
As such modern depictions of Geosaurus, find
that it is actually
more similar to Dakosaurus
As with Dakosaurus, Geosaurus is today thought to have been a short snouted marine crocodile that had large serrated teeth. With this kind of mouth and dentition, Geosaurus would have been a more effective predator of larger fish and potentially even other marine reptiles. Former species of Geosaurus which are now assigned to Cricosaurus indicate that this would have been a form of niche partitioning which allowed several species of marine crocodile to co-exist in the same ecosystem. This would see marine crocodiles like Geosaurus and Dakosaurus taking large prey, while Cricosaurus fed on prey like small fish which it could more easily catch with its longer jaws that had smaller but more numerous teeth.
- Brachytaenius perennis aus dem dichten gelben Jurakalk von Aalen in Würtembertg. In: Meyer H von, Althaus GB, Münster G, eds. - Beiträge zur Petrefacten-kunde. Bayreuth: 22-23, & plate 7 - H. von Meyer - 1842.
- Découverte d’un crocodilien dans le Néocomien de La Martre (Var) Dacosaurus lapparenti n. sp. - Travaux du Laboratoire de la Faculté des Sciences de l'Université de Grenoble 33:89-99 - J. Debelmas & A. Strannoloubsky - 1957.
- Geosaurus vignaudi n. sp. (Crocodylia, Thalattosuchia), first evidence of metriorhynchid crocodilians in the Late Jurassic (Tithonian) of central-east Mexico (State of Puebla) - E. Frey, M. -C. Buchy, W. Stinnesbeck & J. G. López-Oliva - 2002.
- A new thalattosuchian crocodyliform from the Tithonian (Upper Jurassic) of northeastern Mexico - Comptes Rendus Palevol 5 (6): 785-794 - M. -C. Buchy, P. Vignaud, E. Frey, W. Stinnesbeck & A. H. G. González - 2006.
- The evolution and interrelationships of Metriorhynchidae (Crocodyliformes, Thalattosuchia). - Journal of Vertebrate Paleontology 27 (3): 170A - M. T. young - 2007.
- What is Geosaurus? Redescription of Geosaurus giganteus (Thalattosuchia: Metriorhynchidae) from the Upper Jurassic of Bayern, Germany. - Zoological Journal of the Linnean Society, 157: 551-585. - Mark T. Young & Marco Brandalise de Andrade - 2009.
- The oldest known metriorhynchid crocodylian from the Middle Jurassic of North-eastern Italy - Neptunidraco ammoniticus gen. et sp. nov.". Gondwana Research 19 - Andrea Cau & Federico Fanti - 2010.