Oenosaurus
Holotype of Oenosaurus muehlheimensis: skull and mandible in top and side view
- Mörnsheimer layers ( Germany )
- Oenosaurus muehlheimensis Rauhut et al. 2,012
Oenosaurus is an extinct genus of Sphenodontidae from the late Jurassic of Europe. The remains of the single species, Oenosaurus muehlheimensis are from the Mörnsheimer layers in southern Germany. They show alongside typical for modern and extinct Sphenodontidae skull features a specialized dentition, which probably served the cracking of snail and mussel enclosures. Oenosaurus lived in a warm, humid island landscape at the edge of the Tethys and possibly disappeared towards the end of the Jura along with the archipelago.
The hitherto only known fossil of animals, a skull with lower jaw was in 2009 in a quarry near Mülheim, in the Upper Bavarian district of Eichstätt found and described in 2012 by a group of paleontologists to Oliver Rauhut. Oenosaurus is closely related to the recent New Zealand tuatara ( Sphenodon ) and is part of the globally widespread group of Sphenodontia.
Features
The skull of Oenosaurus was relatively robust, triangular-shaped in plan and probably about 28 mm long and wide. Its 33 mm long lower jaw was set with a series of closely stacked plate-like teeth, which formed a continuous layer on the jawbone. The tooth plates consisted of fused, cylindrical dental needles. They were not replaced by regular change of teeth, but grew well throughout life continue to counter their wear. This type of dentition is as atypical as for other terrestrial vertebrates for Sphenodontidae. It occurs in a similar form only in lungfish and short nose chimeras. About the fuselage skeleton of the genus is due to lack of fossils not known.
Locality, fossil material and stratigraphy
The first and only remnants of Oenosaurus, a partially preserved skull with mandibles (inventory number BSPG 2009 I 23 ), were found in a quarry near Mülheim in southern Germany in 2009. They come from the Late Jurassic Mörnsheimer layers of the Franconian Jura, a rock formation that include next lithographing also Kalkmergel with. The Oenosaurus fossils come from the central region of Mörnsheimer layers of marl zone overlying a lime bank. The zone has an age of about 150 million years ago and temporally correlated with the Hybonotum zone of the lower Tithonian.
Ecology
The Franconian Alb was too far back Oenosaurus an archipelago in a relatively shallow Tethys region. The habitat of the lizards were probably shallow coastal or lagoon landscapes, which were influenced by warm, humid climate. The dentition of the animals and their robust jaws suggest a diet of beschalter animal food. It was suitable for cracking hard shells, but it is unclear to which prey could have traded up. Due to the lack of fossil location can not say whether Oenosaurus aquatic or terrestrial lived and thus more likely to come if land snails and insects or shellfish and crabs as prey in question. Probably mainly habitat and climate changes are responsible for the extinction of the species as well as other Sphenodontidae in the early Cretaceous period. In the area of southern Germany archipelago this change came in the form of siltation of the flat sea in appearance.
Systematics and Taxonomy
Gephyrosaurus
Diphydontosaurus
Planocephalosaurus
Homeosaurus
Brachyrhinodon
Clevosaurus hudsoni
C. wangi
Paleopleurosaurus
Pleurosaurus
Kallimodon
Sapheosaurus
Sphenodon
Oenosaurus
Zapatodon
Cynosphenodon
Ophisthias
Toxolophosaurus
Eilodon
Priosphenodon
The first description of Oenosaurus appeared in 2012 in the journal Plos One. The authors Oliver Rauhut, Alexander Heyng, Adriana López- Arbarello and Andreas Hecker chose the generic name Oenosaurus ( Greek " oinos " for wine, " sauros " for lizard ) claims to be based on " the Franconian Alb, a large vineyard "; the epithet muehlheimensis refers to the area where the fossils.
An analysis of the osteological characteristics of fine Oenosaurus and 20 other taxa by the authors showed that the genus is relatively close to the extant tuatara of New Zealand ( genus Sphenodon ) is used. She is the sister taxon of two genera discovered in Mexico, Cynosphenodon and Zapatodon. All three lines separated from each other probably in the Lower Jurassic. While the original diet of this group was probably more or less omnivorous, Oenosaurus be specialized to a comparatively narrow food spectrum. Because of Oenosaurus exists only skull material, but this arrangement is still subject to some uncertainty.