ABSTRACT

Growth layers in insectivores are formed and persist in dentin, cementum, and bone. They are visible in stained sections of decalcified tissues. The annual formation of these layers was proven by studies of animals of known age, by comparisons of age estimates by growth layers and other methods, and also by studies of the recording structures of animals sampled in different seasons of the year. Dentin annual layers, visible on stained sections of the canines, were described in detail in two species of bats, using material from animals of known age. Since that time, growth layers were described in a number of Chiroptera species, both in dentin and in cementum. In rodents having non-evergrowing molars, growth layers can form in cementum, in dentin, and in periosteal bone tissue. Species of this category are studied to a different extent, in particular as far as the possibilities of using their recording structures for age determination are concerned.