THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 49 



Postcanines 



The deciduous lower 1st and 2d postcanines are erupted at birth. 

 The other four pairs erupt a few weeks later. The postcanines are 

 the last deciduous teeth to be replaced by permanent teeth, at an 

 estimated age of 8 to 12 months. The 2d and 3d permanent post- 

 canines erupt in the last quarter of the first year of life. These 

 are the last of the permanent teeth to erupt. As they push upward 

 the deciduous postcanines are raised above their neighbors but 

 remain anchored to the alveolar bone for a considerable period. 

 This condition results in poor occlusion of all tooth surfaces 

 (fig. 26). 



Figure 26. — Intermediate juvenile-adult dentition. At this stage the incisors, 

 two pairs of lower postcanines, one pair of upper postcanines, and molars 

 of the adult dentition are almost fully erupted. The remaining postcanines 

 of the juvenile dentition, however, are still held in place by their extended 

 roots (arrows) above the erupting permanent teeth. The upper photographs 

 demonstrate that these teeth prevent occlusion of the molars and incisors. 

 Many young at this stage are found dead of starvation on beaches. Note 

 abrasion-caused attrition of juvenile teeth. (Juvenile female 62-208, weight 

 22 lb. (10 kg.), length 1,000 mm., found dead on beach, 5 March 1962. 

 (KWK 66-10-15) 



