This volume investigates the complex evolutionary relationships and taxonomic classification of mammalian lineages within the broader context of tetrapod history. M. J. Benton, a distinguished paleontologist, compiles research presented at a landmark 1987 symposium to synthesize the prevailing scientific understanding of mammalian phylogeny. The text utilizes comparative anatomy, fossil record data, and cladistic methodologies to refine the classification systems of various mammalian groups. By aggregating expert contributions, the work establishes a rigorous framework for evaluating the evolutionary transitions that define the mammalian class.

Experts recognize this volume as a foundational reference for vertebrate paleontologists and systematic biologists interested in late 20th-century evolutionary theory. Readers frequently note the academic density of the prose, which is intended for specialists and researchers in the field of evolutionary biology.