Problematic fossils--those groups of organisms that do not fit conveniently into any existing phylum--play a pivotal role in the reconstruction of the history of life, being in effect "early experiments." This lavishly illustrated volume provides careful analyses and descriptions--in anatomical, functional, and developmental terms--of most of the major problematic fossil taxa. Sixteen original papers, written by internationally recognized scholars, discuss the features that make these taxa problematic and that provide clues to their phylogenetic relationships. Since Precambrian groups have been well covered in the existing literature, Hoffman and Nitecki focus on Paleozoic, and especially Early Paleozoic organisms, although Precambrian biota are also discussed.

Determining the precise timing for the evolutionary origin of groups of organisms has become increasingly important as scientists from diverse disciplines attempt to examine rates of anatomical or molecular evolution and correlate intrinsic biological events to extrinsic environmental events. Molecular clock analyses indicate that many major groups

This book embraces general problems of animal classification of animals and new information on their molecular sequences.

Receptaculitids are extinct high-level fossils that provide a window into the history of life. After the discovery and analysis of a deposit of phosphatized receptaculitids on the Baltic Sea island of Öland, the authors conclude that receptaculitids possess an attribute not found in any other group of organisms, living or fossil.

The Encyclopedia of Paleontology is designed to address the shortage of general reference works on both vertebrate and invertebrate paleontology and to serve the needs of students and lay persons interested in the field. As the encyclopedia aims to provide basic information, the majority of the 350 entries are devoted to explanations of paleontological concepts and techniques, examinations of the evolutionary development of particular organisms and biological features, profiles of major discoveries, and biographies of leading scientists. Each entry includes an essay and a further reading list. An international team of 200 leading experts in the field has prepared the illustrations and the essays, which range from concise descriptions to comprehensive discussions.

Most nonscientists are usually aware of fossils, and it is commonly believed that they are extremely rare. In fact, fossils are exceptionally common in many sedimentary rocks and are used extensively in geology for age dating, interpretation of ancient environments, and the discovery of natural resources. However, there is another type of fossil deposit that is truly rare. These rare fossil deposits, called Lagerstätten, preserve the remains of the soft tissues or the articulated skeletal remains of ancient creatures in truly astonishing fine detail. Some of these deposits are world-famous, such as the Burgess Shale, or Solnhofen but there are others dating from many different geological eras from the Paleozoic, up to the Eocene. Recently, a concerted effort has been made to understand the overall significance of these rare fossil deposits. Whereas in the past these deposits were considered novelties, modern researchers are trying to understand what they can tell us about ancient life and environments. New sophisticated techniques (including image and geochemical analyses) are providing enormous new contributions to our knowledge of Lagerstätten sites and to paleobiology in general. This volume describes many of the most famous Lagerstätten locations worldwide and is complete with over 70 superb halftones showing some of these exotic fossils in all their glory. Paleontologists are beginning to understand why such deposits occur, how they have varied since the advent of marine metazoan life, and how their presence effects our understanding of the evolution of life in the Earth's oceans. In this way, the study of Lagerstätten continues to move towards the mainstream of paleobiological, biological, and geological research, and away from its former status as the examination of mere curiosities. All those interested in these beautiful and sometimes enigmatic deposits will want to own this book.

The Cambrian radiation was the explosive evolution of marine life that started 550,000,000 years ago. It ranks as one of the most important episodes in Earth history. This key event in the history of life on our planet changed the marine biosphere and its sedimentary environment forever, requiring a complex interplay of wide-ranging biologic and nonbiologic processes. The Ecology of the Cambrian Radiation offers a comprehensive and surprising picture of the Earth at that ancient time. The book contains contributions from thirty-three authors hailing from ten countries and will be of interest to paleontologists, geologists, biologists, and other researchers interested in the global Earth-life system.