Mesosaurus
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| Mesosaurus Fossil range: Early Permian |
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 restoration of Mesosaurus
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Mesosaurus is an extinct genus of anapsid reptile from the early Permian period. It was about one meter (3 ft) long.
[edit] The return to the water
Mesosaurus was one of the first reptiles to return to the water in which its amphibian ancestors originally lived. Its feet were webbed, its body was streamlined, and its long tail supported a fin. Since the hind legs were much longer, they are presumed to have been used to propel the creature through the water. Its body was flexible and could easily move sideways, but it could not turn as a result of highly thickened ribs (a feature also seen in modern sea cows).
[edit] Skull and teeth
Mesosaurus had a small skull with long jaws. The nostrils were located at the top, allowing the creature to breathe with only the upper side of its head breaking the surface (similar to a crocodile). Mesosaurus's most striking feature were its numerous, thin teeth. Each tooth had its own socket, but were too thin to catch prey. Instead, they are thought to have been used to filter plankton from the water. Fossils of Mesosaurus, a crocodile- like reptile, are found in southern Africa and in South America.
[edit] Distribution
Mesosaurus was significant in providing evidence for the theory of continental drift, because its remains were found in southern Africa and eastern South America, two far away places. As Mesosaurus was a small freshwater organism, and therefore could not have crossed the Atlantic Ocean, this distribution indicated that Africa and South America used to be joined together. Indeed, all the world's continents were joined into one supercontinent called Pangaea in the time Mesosaurus existed.
