THE EDENTATES 165 



eral characters. They are devoid of enamel; their cusps are 

 quickly lost and become replaced by more or less wedge-shaped 

 surfaces, the result of alternate occlusion; they possess perma- 

 nent pulps and are hypsodont in appearance. These features 

 all indicate the very specialized position of the Edentate 

 dentition. 



The American Edentates are well known in Miocene times 

 and there are scattered fragments especially of the Armadillos 

 from yet earlier deposits. Even in the Miocene however the 

 teeth display the same general characters as they do today and 

 the loss of the enamel must therefore be of great antiquity, 

 though even yet a rudiment of the enamel organ persists in 

 the developing teeth. It is quite probable that the American 

 Edentates at least originated from the mammalian stock in 

 Mesozoic times before the differentiation of Insectivora or the 

 ancestors of the Carnivora and of the Ungulata ; indeed some 

 go so far as to suggest for them the formation of a special 

 subclass. 



A glance at the several skulls (Fig. 57) shoAvs at once that 

 there is not much to be learned in the present study from the 

 teeth themselves but there are marked differences in the skulls, 

 in part the result of the dental condition. Naturally the skull 

 varies considerably in form and proportions according to the 

 character of the food and the manner of feeding but very 

 closely associated with these are the type and even the occur- 

 rence of teeth. The Sloths are vegetarians and have a short 

 rounded head with a small face. The Armadillos, largely car- 

 rion feeders, possess a flat low skull with a tapering and more 

 or less elongated muzzle. The Anteaters, the diet of Avhich is 

 indicated by their name, exhibit a long narrow almost cylin- 

 drical skull, the jaws being long and very slender. In the Sloth 

 the condyle of the mandible lies a short distance above the 

 plane of the teeth; in the Armadillo it may be relatively high; 

 in the Anteater the mandible is very attenuated and delicate 

 and possesses only a vestigial condyle raised but slightly above 

 the mandibular body and the coronoid process is almost non- 



