An extinct small aquatic reptile of the early Permian period, with an elongated body, flattened tail, and a long, narrow snout with numerous pointed teeth.
- Genus Mesosaurus, order Mesosauria, subclass Anapsida.
- The most basal anapsids, the mesosaurs, are oldest known fully aquatic reptiles.
- At the same time as the mesosaurs were flourishing in this newly formed inland sea, a major period of mountain building began in the south, due to the Andean-style collision of the Palaeo-Pacific plate under the African plate.
- Only mesosaurs and araeoscelidians demonstrate more lightly built limbs than protorothyridids.
1950s: modern Latin, from Greek mesos 'middle' + sauros 'lizard'.
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Line breaks: meso|saur
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