ABSTRACT
The term 'recording structures' comprises such animal structures as shells of mollusc, scales, otoliths, and bones of fishes, bones of amphibians, reptiles and mammals, dentin and cementum of mammalian teeth, horny substance of claws and horns of some mammals, etc. The period of registration lasts as long as a recording structure grows and forms growth layers. Growth in length of a non-evergrowing tooth may proceed in different ways. Canines of carnivores and true seals, as well as molar teeth of most of the mammals, cease growing in length in the first to third year of life. The enamel, which covers crowns of non-evergrowing teeth, is formed completely before tooth eruption. It is almost pure mineral. When a tooth is decalcified, the enamel, usually, is dissolved completely. Bone tissue, like dentin and cementum, consists of inorganic and organic components. The organic matrix comprises collagen fibers and ground substance.
