This new text sets out to establish the key role played by systematics in deciphering patterns of evolution from the fossil record. It begins by considering the nature of the species in the fossil record and then outlines recent advances in the methodology used to establish phylogenetics relationships, stressing why fossil evidence can be crucial. The way species are grouped into higher taxa, and how this affects their utility in evolutionary studies is also discussed. Because the fossil record abounds with sampling and preservational biases, the book emphasizes that observed patterns can rarely be taken at face value. It is argued that evolutionary trees, constructed from combining phylogenetic and biostratigraphic data, provide the best approach for investigating patterns of evolution through geologic time. The only integrated text covering the study of evolutionary patterns from a phylogenetic stance.