| Stenopterygius | |
|---|---|
 | |
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Kingdom: |
Animalia |
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Phylum: |
Chordata |
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Class: |
Reptilia |
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Order: |
†Ichthyosauria |
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Family: |
†Stenopterygiidae |
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Genus: |
†Stenopterygius |
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Species: |
†S quadriscissus (type) †S. longifrons †S. megalorhius †S. hauffianus |
Stenopterygius was a genus of ichthyosaur from the Middle Jurassic that lived in what is now Europe.
Description[]
Although similar in appearance to the famous Ichthyosaurus, Stenopterygius had narrower flippers and a skull. Like most Jurassic ichthyosaurs, Stenopterygius had a shark-like tail with caudal (tail) fin and a prominent dorsal fin. Its beak-like snout was equipped with a quantity of teeth evolved for catching small fish and cephalopods.
Cannibal or Livebearer?[]
One famous and well-preserved fossil of Stenopterygius was one of an adult with two immature ichthyosaurs within it. It was initially believed that Stenopterygius was a cannibal, preying on its own young. However, if the immature ichthyosaurs had been eaten the would have been facing towards the back of the adult for prey is eaten head-fist. However, the ichthyosaurs inside were facing forward (toward the front of the adult). This left only one explanation: Ichthyosaurs were viviparous (they gave live birth as a pose to laying eggs). The young would have been born tail fist to prevent drowning, as is done with dolphins. This explains why the young Stenopterygius were facing forward inside the adult. The Stenopterygius had died during childbirth.