Kingdom Animalia Infraclass Archosauromorpha Family Teleosauridae Rank Genus | Class Sauropsida Suborder Thalattosuchia Phylum Chordata | |
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Similar Teleosauridae, Thalattosuchia, Metriorhynchidae, Teleosaurus, Pelagosaurus | ||
Steneosaurus is an extinct genus of teleosaurid crocodyliform from the Early Jurassic to Middle Jurassic (Toarcian to Cretaceous). 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.
Contents
Species
Species in this genus are traditionally classed into two skull groups: longirostrine (long, narrow jaws) and brevirostrine (short, broad jaws).
Longirostrine
Brevirostrine
Evolutionary relationships
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.
Niche partitioning
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.
From the semi-aquatic Oker locality in Lower Saxony, Germany (Kimmeridgian-age) two genera of teleosaurids (Steneosaurus and Machimosaurus) are known, in addition to the neosuchian genera Goniopholis and Theriosuchus. Steneosaurus and Machimosaurus are also found together in the same Tithonian-age deposits of western France.