Steneosaurus is an extinct genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of teleosaurid

Teleosauridae

The teleosaurids were marine crocodyliforms similar to the modern gharial that lived from the Early Jurassic to the Early Cretaceous. They had long snouts, indicative of piscivory and were the closest relatives to the Metriorhynchidae, the Mesozoic crocodilians that returned to the sea and evolved...

 crocodyliform from the Early Jurassic

Early Jurassic

The Early Jurassic epoch is the earliest of three epochs of the Jurassic period...

 to Early Cretaceous

Early Cretaceous

The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...

 (Toarcian

Toarcian

The Toarcian is, in the ICS' geologic timescale, an age or stage in the Early or Lower Jurassic. It spans the time between 183.0 Ma and 175.6 Ma...

 to Berriasian

Berriasian

In the geological timescale, the Berriasian is an age or stage of the Early or Lower Creteceous. It is the oldest or lowest subdivision in the entire Cretaceous. It spanned between 145.5 ± 4.0 Ma and 140.2 ± 3.0 Ma...

). Fossil specimens have been found in England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

, France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, Switzerland

Switzerland

Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

 and Morocco

Morocco

Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...

.

Species

Species in this genus are traditionally classed into two skull groups: longirostrine (long, narrow jaws) and brevirostrine (short, broad jaws).
Longirostrine

• S. baroni: Madagascar
  Madagascar
  The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
  
   from the Bathonian
  Bathonian
  In the geologic timescale the Bathonian is an age or stage of the Middle Jurassic. It lasted from approximately 167.7 Ma to around 164.7 Ma...
  
  .
• S. bollensis: Western Europe (England, France and Germany) from the Toarcian.
• S. boutilieri: Western Europe (England, France and Switzerland) from the Bathonian.
• S. gracilirostris: Western Europe (England) from the Toarcian.
• S. heberti: Western Europe (France) from the Callovian and Oxfordian
  Oxfordian stage
  The Oxfordian is, in the ICS' geologic timescale, the earliest age of the Late Jurassic epoch, or the lowest stage of the Upper Jurassic series. It spans the time between 161.2 ± 4 Ma and 155.7 ± 4 Ma...
  
  .
• S. jugleri: Western Europe (Germany and Switzerland) from the late Kimmeridgian and early Tithonian
  Tithonian
  In the geologic timescale the Tithonian is the latest age of the Late Jurassic epoch or the uppermost stage of the Upper Jurassic series. It spans the time between 150.8 ± 4 Ma and 145.5 ± 4 Ma...
  
  . Was originally the type species of the genus Sericodon
• S. larteti: Western Europe (England and France) from the Bathonian.
• S. leedsi: Western Europe (England and France) from the Callovian
  Callovian
  In the geologic timescale, the Callovian is an age or stage in the Middle Jurassic, lasting between 164.7 ± 4.0 Ma and 161.2 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian....
  
  .
• S. megarhinus: Western Europe (England) from the late Kimmeridgian
  Kimmeridgian
  In the geologic timescale, the Kimmeridgian is an age or stage in the Late or Upper Jurassic epoch or series. It spans the time between 155.7 ± 4 Ma and 150.8 ± 4 Ma . The Kimmeridgian follows the Oxfordian and precedes the Tithonian....
  
  .
• S. megistorhynchus: (type
  Type species
  In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
  
  ) Western Europe (France) from the Bathonian.
• S. priscus: Western Europe (Germany) from the early Tithonian. Also is the type species of the genus Aeolodon.

Brevirostrine

• S. brevior: Western Europe (England) from the Toarcian.
• S. edwardsi: Western Europe (England and France) from the Callovian and Oxfordian.
• S. obtusidens: Western Europe (England) from the Callovian.

Evolutionary relationships

A recent phylogenetic analysis into the evolutionary relationships of Thalattosuchia

Thalattosuchia

Thalattosuchia is the name given to a clade of marine crocodylomorphs from the Early Jurassic to the Early Cretaceous that had a cosmopolitan distribution. They are sometimes colloquially referred to as marine crocodiles or sea crocodiles, though they are not actually members of Crocodilia.The term...

 did not support the monophyly

Monophyly

In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...

 of Steneosaurus, as the genera Machimosaurus

Machimosaurus

Machimosaurus is an extinct genus of teleosaurid crocodyliform from the Late Jurassic and Early Cretaceous . The type species, Machimosaurus hugii, was found in France. Other fossils have been found in Austria, England, Germany, Portugal and Switzerland...

and Teleosaurus

Teleosaurus

Teleosaurus was an extinct genus of teleosaurid crocodyliform that lived during the Middle Jurassic. It was approximately in length. Teleosaurus had highly elongate jaws, similar to those of a modern gharial. It had a long, slender, body, with a sinuous tail that would have helped propel it...

both fell within Steneosaurus.

Niche partitioning

Steneosaurus priscus is one of five thalattosuchia

Thalattosuchia

Thalattosuchia is the name given to a clade of marine crocodylomorphs from the Early Jurassic to the Early Cretaceous that had a cosmopolitan distribution. They are sometimes colloquially referred to as marine crocodiles or sea crocodiles, though they are not actually members of Crocodilia.The term...

n species known from the Mörnsheim Formation (Solnhofen limestone

Solnhofen limestone

The Solnhofen Plattenkalk is a Jurassic Konservat-Lagerstätte that preserves a rare assemblage of fossilized organisms, including highly detailed imprints of soft bodied organisms such as sea jellies...

, early Tithonian) of Bavaria

Bavaria

Bavaria, formally the Free State of Bavaria is a state of Germany, located in the southeast of Germany. With an area of , it is the largest state by area, forming almost 20% of the total land area of Germany...

, Germany. Steneosaurus was the only teleosaurid known from this Formation, co-existing with four metriorhynchid

Metriorhynchidae

Metriorhynchidae is an extinct family of metriorhynchoid crocodyliforms from the Middle Jurassic to the Early Cretaceous period of Europe, North America and South America. Metriorhynchids are fully aquatic crocodyliforms. Their forelimbs were small and paddle-like, and unlike living crocodilians,...

 species from the genera Dakosaurus

Dakosaurus

Dakosaurus is an extinct genus within the family Metriorhynchidae that lived during the Late Jurassic and Early Cretaceous. It was large, with teeth that were serrated and compressed lateromedially . The genus was established by Friedrich August von Quenstedt in 1856 for an isolated tooth named...

and Geosaurus

Geosaurus

Geosaurus is an extinct genus of marine crocodyliform within the family Metriorhynchidae that lived during the Late Jurassic to the Early Cretaceous. Geosaurus was a carnivore that spent much, if not all, its life out at sea...

. It has been hypothesised that niche partitioning

Niche differentiation

The term niche differentiation , as it applies to the field of ecology, refers to the process by which natural selection drives competing species into different patterns of resource use or different niches...

 enabled several species of crocodyliforms to co-exist.

From the semi-aquatic Oker locality in Lower Saxony

Lower Saxony

Lower Saxony is a German state situated in north-western Germany and is second in area and fourth in population among the sixteen states of Germany...

, Germany (Kimmeridgian

Kimmeridgian

In the geologic timescale, the Kimmeridgian is an age or stage in the Late or Upper Jurassic epoch or series. It spans the time between 155.7 ± 4 Ma and 150.8 ± 4 Ma . The Kimmeridgian follows the Oxfordian and precedes the Tithonian....

-age) two genera of teleosaurids (Steneosaurus and Machimosaurus

Machimosaurus

Machimosaurus is an extinct genus of teleosaurid crocodyliform from the Late Jurassic and Early Cretaceous . The type species, Machimosaurus hugii, was found in France. Other fossils have been found in Austria, England, Germany, Portugal and Switzerland...

) are known, in addition to the neosuchian genera Goniopholis

Goniopholis

Goniopholis is an extinct genus of crocodyliform that lived in North America, Europe and Asia during the Late Jurassic and Early Cretaceous. Being semi-aquatic it is very similar to modern crocodiles...

and Theriosuchus

Theriosuchus

Theriosuchus is an extinct genus of atoposaurid mesoeucrocodylian from the Late Jurassic of Europe, the Early Cretaceous of Asia and the Late Cretaceous of Romania. The five species are T. pusillus from England , T. ibericus from Spain , T. guimarotae from Portugal , T. sympiestodon from Romania...

. Steneosaurus and Machimosaurus are also found together in the same Tithonian-age deposits of western France.