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Ichthyosaurs |
Ichthyosaurs looked similar to modern dolphins in shape, but are completely unrelated to them. Ichthyosaurs are marine reptiles whereas dolphins are mammals, and swam in the seas long before dolphins had evolved. The type of ichthyosaur that is found in the Oxford Clay is Ophthalmosaurus. It was given this name because of its big eyes which it used to see in poor light. This could indicate either that it dived deep into the dark depths or hunted at dusk and dawn. Unlike the ichthyosaurs from earlier in the Jurassic Ophthalmosaurus had very small teeth and so probably fed on soft bodied prey.
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Please click on thumbnails to view larger image |
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Femur of Ophthalmosaurus |
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Lower Jurassic ichthyosaurs had large interlocking teeth. |
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Ichthyosaur vertebrae are biconcave discs. A Y-shaped bone called the neural process protects the Spinal chord below it. In Ichthyosaurs the neural arch and centrum are always separate bones. Body vertebrae have two attachments for ribs (R), tail vertebrae only have one. |
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Body vertebra |
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Ophthalmosaur skull Can you see the large eye socket? The eyes had a ring of bone called a sclerotic ring to support them. |
