ABSTRACT
Considering investigation of recording structures of animals of different systematic groups, it is interesting to compare the achievements of theriologists and of specialists in other groups of animals. The first steps in the age determination of mammals by the number of annual layers were made when, in ichthyology and malacology, it has already become to routine practice to use annual layers for ageing animals and for back-calculating the growth of individuals. In age determination, theriologists faced difficulties that had been known for a long time by ichthyologists and malacologists, such as inter- and intraspecific variations in growth layer pattern, which hinders the detection of an annual layer. Malacologists and ichthyologists use recording structures of mollusc and fish for obtaining data on the season of birth and death of individuals, on breeding, and on the degree of mutual isolation of intraspecific local groups.
