Definition of mesosaur in English:

Share this entry


Pronunciation: /ˈmezəˌsôr/ /ˈmē-/
(also mesosaurus /ˌmezəˈsôrəs/)


An extinct small aquatic reptile of the early Permian period, with an elongated body, flattened tail, and a long narrow snout with numerous needlelike teeth.
  • Genus Mesosaurus, order Mesosauria, subclass Anapsida.
Example sentences
  • 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.



Example sentences
  • If the shales at Kimberley are Lower Karroo rocks, then, from the occurrence of Mesosaurus on that horizon, those rocks may be termed Mesosaurian.
  • The study here developed on the metric relationships of mesosaurian teeth proved to be useful for the identification of isolated pieces.


1950s: modern Latin, from Greek mesos 'middle' + sauros 'lizard'.

For editors and proofreaders

Syllabification: mes·o·saur

Share this entry

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.