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Pleurosaurus was a member of the aquatic Pleurosauridae. This group of extinct specialized sphenodonts first evolved on land, and then returned to the water during Early Jurassic times, possibly because there was too much competition on the land. The only specific aquatic adaptation among pleurosaurs seems to have been a great elongation of the body. They had up to 57 vertebrae, twice the typical sphenodont number. Snakelike movementsof the long sinuous body and tail moved Pleurosaurus rapidly through the water. Its nostrils zere set far back on its snout, near the eyes. its legs were much shorter than those of land-living sphenodonts, and played no role in swimming.
Author: Koen Stein
Last updated: 21/11/2005
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