PLESIOSAURS. 



59 



Oxford and Kimmeridge Clays the head is large and the neck short, 

 while the teeth may be trihedral instead of conical. The upper arches 

 of the vertebrae were loosely attached to the bodies. 



The smaller Triassic representatives of the group, such as 

 Neusticosaurus (343) and Lariosaurus (342), were probably amphi- 

 bious or terrestrial, and had limbs of a more normal structure. They 

 approach the primitive Rhynchocephalia. 



In some restorations, Plesiosaurs are represented with the neck 



