''Steneosaurus'' (from el, στενός , 'narrow' and el, σαῦρος , 'lizard') is a dubious

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

teleosaurid Teleosauridae is a family of extinct typically marine crocodylomorphs similar to the modern gharial that lived during the Jurassic period. Teleosaurids were thalattosuchians closely related to the fully aquatic metriorhynchoids, but were les ...

crocodyliform Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseu ...

from the Middle or

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

( Callovian or early Oxfordian) of

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

. The genus has been used as a wastebasket taxon for thalattosuchian fossils for over two centuries, and almost all known historical species of teleosauroid have been included within it at one point. The genus has remained a wastebasket, with numerous species still included under the label ''‘Steneosaurus’'', many of which are unrelated to each other (either

paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...

with respect to each other and other genera of teleosauroids).

Discovery and assigned species

The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specim ...

, ''S. rostromajor'', was only formally recognised as such in 2020, and this revision determined the

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...

of ''Steneosaurus'' was undiagnostic, and so declared the genus ''Steneosaurus'' a ''nomen dubium''. The history of this specimen has been detailed in 2017. It was discovered in three pieces by abbot Charles Bacheley (1716-1795) in the Vaches Noires near Villers-sur-Mer (Calvados, France). Bacheley offered these pieces to Alexandre Besson (1725-1809) who had built up an important cabinet of fossils and minerals in Paris. Besson gave one of the pieces (the posterior portion) to Barthélémy Faujas de Saint-Fond (1841-1819), professor of geology in the Muséum national d'Histoire naturelle, Paris. Georges Cuvier first illustrated in 1808 the two anterior pieces of the specimen kept in the Besson collection and then figured the third piece (posterior portion from the Faujas de Saint-Fond collection) in 1824 in association with the anterior pieces (Besson collection) and other cranial remains belonging to Metriorhynchidae. The remaining species referred to ''Steneosaurus'' thus require new generic names, and some species have already been assigned to new genera prior to ''Steneosaurus'' being declared a ''nomen dubium''. Species in this genus are traditionally classed into two skull groups: longirostrine (long, narrow jaws) and mesorostrine (slightly shorter jaws). ;Longirostrine * S.' atelestatus'' - Oxfordian

Marnes de Villers The Marnes de Villers is a geologic formation in France. It preserves fossils dating back to the Late Jurassic period. Paleofauna *Allosauroidea indet. - possible metriacanthosaurid *''Leedsichthys'' *Megalosauridae indet. - Similar to ''Torvos ...

of France * S.' blumembachi'' - Oxfordian Marnes de Villers of France * S.' oplites'' - Toarcian La Caine-Curcy of France * S.' rudis'' - France Additional ''Steneosaurus'' fossils not attributed to a specific genus have been found in: * Bathonian El Mers Formation, Morocco * Bathonian Techout Formation, Tunisia * Jurassic Czarnogłowy, Poland

Reassigned species

* Steneosaurus' baroni'' = ''

Andrianavoay ''Andrianavoay'' (meaning "noble crocodile" in Malagasy) is an extinct genus of teleosauroid from the Bathonian (in the Middle Jurassic) Kandreho Formation of Madagascar. The type species, ''A. baroni'', was originally named "''Steneosaurus ...

'' * Steneosaurus' bollensis'' = ''

Macrospondylus ''Macrospondylus'' is an extinct genus of machimosaurid teleosauroid crocodyliform from the Early Jurassic (Toarcian) of Europe. Fossils are known from the Posidonia Shale of Germany, the Whitby Mudstone of the United Kingdom, and the "'' sch ...

'' * S.' bouchardi'' - = ''

Proexochokefalos ''Proexochokefalos'' (meaning "big head with big tuberosities") is an extinct genus of machimosaurid teleosauroid from the Jurassic of France Classification The type species, ''S. heberti'', was originally named "''Steneosaurus''" ''heberti'' ...

'' * Steneosaurus' boutilieri'' = ''

Yvridiosuchus ''Yvridiosuchus'' (meaning "hybrid crocodile") is an extinct genus of machimosaurid crocodyliform from the Middle Jurassic (Bathonian) Cornbrash Formation of England and the '' Sommet de la Grande Oolithe'', Calvados Calvados (, , ) is a ...

'' * Steneosaurus' brevior'' = '' Mystriosaurus'' * Steneosaurus' deslongchampsianus'' * Steneosaurus' edwardsi'' = ''

Neosteneosaurus ''Neosteneosaurus'' is a genus of machimosaurid, known from the Middle Jurassic Oxford Clay of the UK, and Marnes de Dives, France. The type species, ''N. edwardsi'', was originally named as a species of ''Steneosaurus'' in 1868, but was moved ...

'' * Steneosaurus' gracilirostris'' = '' Plagiophthalmosuchus'' * Steneosaurus' heberti'' = ''

'' * Steneosaurus' larteti'' = '' Deslongchampsina'' * Steneosaurus' leedsi'' = '' Charitomenosuchus'' * Steneosaurus' megarhinus'' = ''

Bathysuchus ''Bathysuchus'' ("deep water crocodile") is an extinct genus of teleosaurid thalattosuchian from Late Jurassic ( Kimmeridgian) deep water marine deposits in England and France. ''Bathysuchus'' displays features that suggest it was more pelag ...

'' * Steneosaurus' megistorhynchus'' = '' Seldsienean'' * Steneosaurus' obtusidens'' = '' Lemmysuchus''

Classification

A 2005

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups ...

analysis into the evolutionary relationships of

Thalattosuchia Thalattosuchia is a clade of marine crocodylomorphs from the Early Jurassic to the Early Cretaceous that had a cosmopolitan distribution. They are colloquially referred to as marine crocodiles or sea crocodiles, though they are not members of Cro ...

did not support the

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...

of ''Steneosaurus'', as the genera ''

Machimosaurus ''Machimosaurus'' is an extinct genus of machimosaurid crocodyliform from the Late Jurassic ( Kimmeridgian and Tithonian) and Early Cretaceous. The type species, ''Machimosaurus hugii'', was found in Switzerland. Other fossils have been f ...

'' and ''

Teleosaurus ''Teleosaurus'' (from el, τέλειος , 'perfect' and el, σαῦρος , 'lizard') is an extinct genus of teleosaurid crocodyliform found in the Middle Jurassic Calcaire de Caen Formation of France. It was approximately in length and wei ...

'' both fell within ''Steneosaurus''. Reinforcing the paraphyly of ''Steneosaurus'', the Callovian species ''"Steneosaurus" obtusidens'' has been recovered as the sister species of ''Machimosaurus'' in recent cladistic analyses of Thalattosuchia and renamed '' Lemmysuchus'', while Steneosaurus' bollensis'' was recovered in a basal position to other members of ''Steneosaurus sensu lato''.

References

External links

Angellis Net pdf
{{Taxonbar, from=Q137074 Thalattosuchians Prehistoric pseudosuchian genera Prehistoric marine crocodylomorphs Early Jurassic crocodylomorphs Middle Jurassic crocodylomorphs Aalenian life Bajocian life Bathonian life Callovian life Toarcian life Early Jurassic reptiles of Europe Middle Jurassic reptiles of Europe Fossils of England Oxford Clay Fossils of France Fossils of Germany Solnhofen fauna Jurassic reptiles of Africa Fossils of Morocco Fossils of Tunisia Fossil taxa described in 1825 Nomina dubia

Discovery and assigned species

Reassigned species

Classification

See also

References

External links