As scientific analysis of testable hypotheses has replaced the speculative approach to study of bone disease in recent and fossil amphibians and reptiles, the field has advanced from simply reporting observations to analyzing their implications. This process is predicated upon a reproducible data base which explains/diagnoses the nature of bony alterations and a secure review of the literature. Thereby hangs the rub. The herpetological literature are difficult to access (let alone read) and are scattered through many prominent and eclectic journals and in the lay literature. While older diagnoses often have not stood the test of time, the clarity of report descriptions usually allows confident identification of the underlying pathology.

This edited volume explores the various views on the origins of tetrapods-amphibians, reptiles, birds, and mammals-views that agree or differ depending in part on how certain fossil animals are classified and which methodology is used for classification. Eighteen chapters by an international group of paleontologists and neontologists here present current hypotheses, emphasizing the kinds of data needed to answer controversial questions, as well as the variety of solutions that emerge from diferent analyses of the same data set. The book is arranged in five sections, each of which contains an overview essay that either describes the development of various schools of thought regarding the origin of the tetrapod group in question or critically summarizes the arguments presented in the section. The first section addresses the origins of tetrapods as a group, focusing on lobe-finned fishes and early tetrapods. Next is a section dealing with amphbians, followed by one on reptiles. The fourth section concerns avian origins, and the final section treats the origins and early diversification of mammals. With an overall goal of stimulating critical evaluation by the reader rather than providing unequivocal answers, this volume will be of particaular interest to vertebrate paleontologists, evolutionary morphologists, and ichthyological, herpatological, avian, and mammalian systematists.