Mixosaurus and Shonisaurus

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In appearance Mixosaurus seems intermediary between the ccl-like forms typified by CyttibospondyluSy and the more familiar dolphin-shaped forms such as the later Ichthyosaurus hence the name, rhe long tail with its low fin suggests that it was a slow swimmer, moving forward by undulation of the tail.


Features: The body and tail are long, with the tail having a low fin that is not as well-developed as the shark- like fin of the later types, and there is a stabilizing dorsal fin on the back. The paddle-like limbs are still made up of five toes each, unlike the multi-toedstructure found in later ichthyosaurs. However, each toe has moreindividual bones than is usual (polyphalangy) and the front limbs are longer than the rear.






In the 1920s miners found a deposit of huge hones in Nevada. When they were excavated 30 years later they were found to he the remains of 37 individual enormous ichrhyosaurs, and were named Shonisaurus. Fhey may have been a shoal that was beached, or cut off from the sea. More recently, the scientific view is that they died and sank to the sea bed.


Features: This ichthyosaur has a whale-like shape and long narrow paddles. It has teeth only at the front of the jaws. S. popularis held the record as the biggest of the ichthyosaurus, but the skeleton of an even bigger species. S. stkanniensis, was found in the 1990s in British Columbia. With an estimated length of 21m (70ft). this was so big it could only have been seen in its entirety from the air. Studies of this new species suggest that Shonisaurus may not have been asdeep-bodied as originally thought.


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