TRENDS IN THE EVOLUTION OF REGIONAL FAUNAS REGULAR ARCHAEOCYATHIDS

Archaeocyathid fauna renewals are traced in eleven regions by dividing new genera of every chron into three groups: (1) immigrant genera, or colonizers; (2) aboriginal genera; and (3) genera, whose generation a reas raise doubts. It is shown that dominant genera of the second grou p are important for detecting secondary centers of origin, while most abundant genera of the first group point to biotic invasions in the re gions. The taxa prevalence in the third group is related to transgress ions. Endemic genera mark the progressing specialization of taxa, but not the isolation of a region. As a rule, they appear in the centers o f origin, and at the moments of peak diversity. Also analyzed are the growth, diversification, and regressive evolutionary stages of regiona l faunas.