plesiosaur

plesio- +‎ -saur

plesiosaur (plural plesiosaurs)

1. Any of several extinct marine reptiles, of the order Plesiosauria, from the Jurassic and Cretaceous periods. [from c. 1840]
   • 1918, Edgar Rice Burroughs, The Land That Time Forgot Chapter IV

     "Look!" cried Olson. "Would you look at the giraffe comin' up out o' the bottom of the say?" We looked in the direction he pointed and saw a long, glossy neck surmounted by a small head rising above the surface of the river. Presently the back of the creature was exposed, brown and glossy as the water dripped from it. It turned its eyes upon us, opened its lizard-like mouth, emitted a shrill hiss and came for us. The thing must have been sixteen or eighteen feet in length and closely resembled pictures I had seen of restored plesiosaurs of the lower Jurassic.

   Synonym: plesiosaurus