Macrospondylus

Steneosaurus Temporal range: 183–163 Ma PreЄ Є O S D C P T J K Pg N Toarcian – Callovian
Steneosaurus bollensis, Holzmaden Germany
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Infraclass:	Archosauromorpha
(unranked):	Mesoeucrocodylia
Suborder:	Thalattosuchia
Family:	Teleosauridae
Genus:	Steneosaurus Geoffroy, 1825
Species
S. baroni Newton, 1893 ?S. bollensis (Jaeger, 1828) S. boutilieri Eudes-Deslongchamps, 1869 ?S. brevior Blake in Tate and Blake, 1876 S. edwardsi (Eudes-Deslongchamps, 1868) ?S. gracilirostris Westphal, 1961 S. heberti Morel de Glasville, 1876 S. larteti (Eudes-Deslongchamps, 1868) ?S. leedsi Andrews, 1909 ?S. megistorhynchus (Geoffrey Saint-Hilaire in Eudes-Deslongchamps, 1869) S. pictaviensis Vignaud, 1998 S. rostromajor Geoffey Saint Hilaire, 1825 (type) ?S. obtusidens Andrews, 1909
Synonyms
?Macrospondylus Von Meyer, 1830 Mycterosuchus Andrews, 1913 Mystriosaurus Munster, 1834

Steneosaurus is an extinct genus of teleosaurid crocodyliform from the Early Jurassic to Middle Jurassic (Toarcian to Callovian). Fossil specimens have been found in England, France, Germany, Switzerland and Morocco. The largest species, S. heberti, reached up to 5 m (16.5 ft) long, though 2.5–3.5 m was far more common.

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

Longirostrine

Brevirostrine

A 2005 phylogenetic analysis into the evolutionary relationships of Thalattosuchia did not support the monophyly of Steneosaurus, as the genera Machimosaurus and Teleosaurus 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, while Steneosaurus bollensis was recovered in a basal position to other members of Steneosaurus sensu lato. Given the paraphyly of Steneosaurus, Macrospondylus von Meyer, 1830 is the earliest available generic name for S. bollensis.

Steneosaurus (=Aeolodon) priscus is one of five thalattosuchian species known from the Mörnsheim Formation (Solnhofen limestone, early Tithonian) of Bavaria, Germany. Steneosaurus was the only teleosaurid known from this Formation, co-existing with four metriorhynchid species: Dakosaurus maximus, Geosaurus giganteus, Cricosaurus suevicus and Rhacheosaurus gracilis. It has been hypothesised that niche partitioning enabled several species of crocodyliforms to co-exist. D. maximus and G. giganteus would have been top predators of this Formation, both of which were large, short-snouted species with serrated teeth. The remaining species (S. priscus, C. suevicus and R. gracilis) would have fed mostly on fish.

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Wikipedia