Ichthyosaur Fossil | Stenopterygius quadriscissus | Germany
Stenopterygius quadriscissus
Early Jurassic (~180 MYO)
Posidonia Shale
Holzmaden, Germany
Ichthyosaur approx. size: 40.5" x 10.75"
Plate approx. size: 55.25" x 21.75" x 1.25", 2.75" for the bracket.
This piece has had some restoration.
Stenopterygius quadriscissus is a small-to-medium sized ichthyosaur that lived during the early Jurassic, approximately 180 million years ago. It had a streamlined, tuna- or dolphin-like body, but was a reptile rather than a fish or mammal.
The species is particularly famous from the Posidonia Shale around Holzmaden, Germany, where exceptionally preserved fossils can retain articulated skeletons with soft-tissue outlines. Some fossils retain evidence of the body contour, fins, and even reproductive events.
Typical fossil features include:
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A long, narrow snout containing numerous small teeth, although teeth could become greatly reduced or even disappear in mature individuals.
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A large, streamlined body with four paddle-like limbs, the front flippers being substantially larger than the hind flippers.
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A flexible vertebral column ending in a downward-bending tail that supported a crescent-shaped tail fin.
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A dorsal fin and streamlined body outline, adaptations associated with fast swimming.
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A relatively compact skull and elongated jaws.
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Usually five digits in the forefin, although four or six can occur.
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A skeleton that is often preserved laterally compressed and articulated in the fine-grained shale.
The anatomy indicates a fast-swimming pelagic predator. Its streamlined body, large eyes, powerful tail, and efficient paddles suggest active pursuit of fish and other marine prey. Unlike most modern reptiles, ichthyosaurs were fully adapted to an open-marine existence and retained air-breathing lungs.
One of the most remarkable things about S. quadriscissus fossils is that some specimens preserved pregnancy and live birth. A famous specimen at the American Museum of Natural History preserved an adult with developing young, demonstrating that ichthyosaurs gave birth to live young rather than laying eggs.