During which geological period of evolution did the greatest diversification of life occurred on the earth?

The Cambrian explosion in Cambrian period marks the occurrence of greatest diversification on the earth. Most major phyla appeared (indicated by fossil study), divergence of modern Metazoan phyla occurred and major diversification of other organisms. Before this period, most organisms were simple however, this changed after Cambrian period, diversification rate accelerated and the diversity of life began to resemble that of today.