Mesosaurus

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iMesosaurus Fossil range: Early Permian
Mesosaurus skeleton
Conservation status
Extinct (fossil)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Sauropsida Order: Mesosauria Family: Mesosauridae Genus: Mesosaurus

Mesosaurus is an extinct genus of anapsid reptile from the Permian period. It was about 1 m (3 ft 4 in) long.

[edit] The return to the water

Mesosaurus was one of the first reptiles to return to the water where its amphibian ancestors originally came from. Its feet were webbed, body 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.

[edit] Distribution

Mesosaurus was significant in the providing evidence of the theory of continental drift, because its remains were found in southern Africa and eastern South America, two far away places. As Mesosaurus lived in fresh water, 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.