mesosaur

 
Pronunciation: /ˈmɛsəsɔː/

noun

  • 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

Origin:

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