During the last ZO years great progress has been achieved in our understanding of both earth history and vertebrate evolution. The result is that climatic/tectonic events in earth history can now be placed in a more precise and global time frame, that permit their evaluation as abiotic causal factors which might trigger extinction and dispersal events in vertebrate history. Great strides have also been made in genetics and cell biology, providing new insight into phylogenetic relationships among many vertebrates. These new data, along with data on chronologie resolution of earth history,...