Oenosaurus
| Oenosaurus | ||||||||||||
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Holotype of Oenosaurus muehlheimensis : skull and lower jaw in top and side view |
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| Temporal occurrence | ||||||||||||
| Upper Jurassic ( Tithonian ) | ||||||||||||
| 152.1 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Oenosaurus | ||||||||||||
| Rauhut , Heyng , López-Arbarello & Hecker , 2012 | ||||||||||||
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Oenosaurus is an extinct genus of the Sphenodontidae from the late Jurassic Europe . The remains of the only species , Oenosaurus muehlheimensis , come from the Mörnsheim strata in southern Germany . In addition to skull features typical of modern and extinct Sphenodontidae, they show specialized dentition, which was probably used to crack snail and mussel shells. Oenosaurus lived in a warm, humid island landscape on the edge of the Tethys and possibly disappeared together with the archipelago towards the end of the Jurassic.
The only known fossil of the animals to date, a skull with a lower jaw, was found in a quarry near Mühlheim , in the Upper Bavarian district of Eichstätt , and described in 2012 by a group of paleontologists led by Oliver Rauhut . Oenosaurus is closely related to the recent New Zealand bridge lizards ( Sphenodon ) and is part of the worldwide group of Sphenodontia .
features
The skull of Oenosaurus was comparatively robust, triangular in shape when viewed from above and probably around 28 mm long and wide. Its 33 mm long lower jaw was covered with a series of densely layered, plate-shaped teeth that formed a continuous layer on the jawbone. The tooth plates consisted of fused, cylindrical tooth needles. They were not replaced by regular tooth changes, but probably continued to grow throughout life to counteract their wear and tear. This type of dentition is just as untypical for Sphenodontidae as it is for other terrestrial vertebrates. It occurs in a similar form only in lung fish and short-nosed chimeras . Nothing is known about the trunk skeleton of the genus due to a lack of fossil finds.
Site, fossil material and stratigraphy
The first and so far only remains of Oenosaurus , a partially preserved skull with lower jaws ( inventory number BSPG 2009 I 23), were found in 2009 in a quarry near Mühlheim in southern Germany . They come from the late Jurassic Mörnsheimer strata of the Franconian Alb , a rock formation that includes limestone as well as limestone marl . The Oenosaurus fossils come from the middle area of the Mörnsheimer strata, a marl zone that lies over a limestone bank. The zone has an age of 150 million years ago and temporally correlated with the Hybonotum zone of the lower Tithonian .
ecology
During the lifetime of Oenosaurus, the Franconian Alb was an archipelago in a relatively shallow Tethys region. The habitat of the lizards was probably flat coastal or lagoon landscapes, which were characterized by a warm and humid climate. The teeth of the animals and their sturdy jaws suggest a diet of poor animal food. It was suitable for cracking hard shells, but it is unclear which prey it could have been. Due to the inadequate fossil record, it cannot be said whether Oenosaurus lived aquatic or terrestrial and whether land snails and insects or mussels and crabs are more likely to be prey. For the extinction of the genus as well as other Sphenodontidae in the early Cretaceous period, habitat and climate changes are primarily responsible. In the area of the southern German archipelago, this change took the form of silting up of the shallow sea .
Systematics and taxonomy
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| Systematic position of Oenosaurus according to Rauhut et al. (2012). The genus is part of the Sphenodontinae and is historically close to the bridge lizards ( Sphenodon ). |
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) according to their own statements based on "the Franconian Alb, an important wine-growing region"; the specific epithet muehlheimensis refers to the place where the fossils were found.
An analysis of the osteological fine features of Oenosaurus and 20 other taxa by the authors showed that the genus is relatively closely related to the recent bridge lizards of New Zealand (genus Sphenodon ). It is the sister taxon of two genera discovered in Mexico , Cynosphenodon and Zapatodon . All three lines probably separated from each other in the Lower Jurassic . While the original diet of this group was probably more or less omnivorous , Oenosaurus specialized in a relatively narrow range of foods. Since only skull material is available from Oenosaurus , this classification is still subject to a certain degree of uncertainty.
swell
literature
- Oliver WM Rauhut, Alexander M. Heyng, Adriana López-Arbarello, Andreas Hecker: A New Rhynchocephalian from the Late Jurassic of Germany with a Dentition That Is Unique Amongst Tetrapods. In: Plos One. 7 (10), 2012, e46839, doi : 10.1371 / journal.pone.0046839 , pp. 1–9 ( full text ).
