REPTILES 365 



place of articulation with the first vertebra. In this, 

 reptiles agree with birds, and differ from amphibians 

 and mammals. On account of this character, it used 

 to be supposed that the mammals had arisen directly 

 from the amphibians ; but more recently fossils have 

 been found in South Africa which are distinctly reptilian, 

 and approach the mammals more closely than any 

 amphibian. These ancient animals, the cynodont or 

 dog-toothed reptiles, had paired occipital condyles and 

 the teeth distinctly differentiated into incisors, canines, 

 premolars, and molars. Presumably they were cold- 

 blooded and without hair, but we have no knowledge 

 of anything but their bones and teeth. 



3. The classification of living reptiles is relatively ciassifica- 

 simple, because we have today only the remnants of re p u es 

 a mighty host. Numerous and diverse as are the species 

 of snakes, lizards, and turtles, they appear insignifi- 

 cant beside the dinosaurs, plesiosaurs, pterosaurs, and 

 ichthyosaurs of several million years ago. It was in the 

 Mesozoic age that the reptiles reached the maximum of 

 size and diversity of structure, - - a time when the 

 mammals were small and insignificant, apparently 

 promising little for the future. There still exists in New 

 Zealand a remnant of the Mesozoic reptilian fauna, the 

 tuatera of the Maoris, Sphenodon of the naturalists. 

 This animal, now almost extinct, resembles a large 

 lizard, the back ornamented with spines. The structure 

 of the skeleton shows that it has nothing to do with the 

 lizards, but is related to some of the most ancient fossil 

 forms ; it is a relic of antiquity which has managed to 

 survive in an isolated part of the world, free from com- 

 petition. 



6. Parallel or analogous adaptations are common 

 among animals, and thus we find that millions of years 



