THE ANALYSIS OF AGE STRUCTURE OF HIGH RAN GE TAXA

The evolutionary changes of age structure of high range taxa were exam ined. To take into consideration the diversity of age structure at eac h time (century)and the degree of dominance the author used the inform ation index of evenness (Shannon index). Descending trend of evenness index is typical for taxa with low and medium duration of existence wh ich developed mainly in one or few directions, for instance Fusulinace a, Nautiloidea, Favositida and some sea urchins. Ascending trend and f luctuations around certain level characterize the strategy supporting many evolutionary directions, for example Bivalvia, Spatangoida, repti les, mammals.