Important method of measuring the rate of evolution consists in measuring the number of new species or arbitrary higher taxa formed within a certain line or that, on the other hand, disappear over a certain time interval (Simpson 1944). The method is based on the assumption that new species or higher taxa are defined by an expert on the particular group on the basis of a greater number of traits, taking into account the overall intraspecies and interspecies variability within the entire relevant taxon, and of the mutual interconnection or, to the contrary, independence of the changes in the individual traits. The individual traits and thus also evolutionary changes are often mutually dependent and thus a change in a certain trait for functional or ecological reasons can be automatically accompanied by changes in an entire range of other traits. Two forms of an organism that differ in a set of 50 interconnected traits can thus be much closer than two forms that differ in 5 independent traits. The number of new species formed in a certain time interval should thus reflect more accurately the rate of evolution of the given group rather than mechanically correspond to the sum of the number of traits that change in the given period within the particular taxon. The rate measured in terms of changes in the number of species per time interval, most frequently the fraction of species that became extinct in this interval, is termed the taxonomic rate. Once again, it holds that it is necessary to compare taxonomic rates within a single line or at least within related lines. Further, it is necessary to take into consideration changes in the numbers of species within the particular line; it is not possible to mechanically compare the taxonomic rate of a line that is dying out at the particular time with the taxonomic rate of a line that is in equilibrium state or that is growing.