28 COMPARATIVE DENTAL ANATOMY 



without fear of contradiction, that only those ani- 

 mals have existed whose dental apparatus has 

 been able to change to meet their needs. We find 

 many fossils, which have disappeared because 

 their dental apparatus was not suited to their par* 

 ticular needs. 



The first function in the securing of the food 

 is prehension, or the seizing of the food sub- 

 stances. It is the only function which the teeth 

 perform in some fishes and reptiles. The second 

 to appear in the animal kingdom was deglutition. 

 Deglutition is the principal function of the teeth 

 located on the vomer and palates of most of the 

 fishes and is one of the principal functions of the 

 teeth of the non-poisonous snakes. Incision, or 

 the cutting of the food into pieces, was the next 

 function to appear. In some animals, we find 

 incision has to a certain extent taken the place 

 of prehension; this may be said of the teeth of 

 man, as the incisors are well developed. In some 

 of the lower animals, the anterior teeth are shaped 

 like incisors, an example of which is the sargus. 

 The next step or function was the crushing of 

 the food, which was first done by blunt flat teeth 

 or by pavement teeth. Then came the function 

 of grinding the food or mastication, which was 

 performed by teeth of various shapes, depending 

 upon the class of food. Insalivation is the last 

 function of the teeth and is the mixing of the 



