pelycosaur

from WordNet (r) 3.0 (2006)

pelycosaur
    n 1: large primitive reptile having a tall spinal sail; of the
         Permian or late Paleozoic in Europe and North America

from The Collaborative International Dictionary of English v.0.48

pelycosaur \pelycosaur\ n.
   1. A large primitive reptile having a tall spinal sail; of
      the Permian or late Paleozoic in Europe and North America.
      [WordNet 1.5]