The Nature of the Fossil Record: A Biological Perspective.- Natural Selection and Fitness, Adaptation and Constraint.- Directions in the History of Life Group Report.- The Evolution and Ecology of Body Size.- Progress in Organismal Design.- Time Series Analysis of the Fossil Record.- The Systems Approach: An Interface between Developmental and Population Genetic Aspects of Evolution.- Organismic Evolution: The Interaction of Microevolutionary and Macroevolutionary Processes Group Report.- The Genetics of Adaptive Radiation: A Neo-Darwinian Theory of Punctuational Evolution.- Fossil Record of the Origin of Baupläne and Its Implications.- Molecular Phylogeny.- Causes and Consequences of Extinction Group Report.- The Proximate Causes of Extinction.- Phanerozoic Overview of Mass Extinction.- Environmental Changes in Times of Biotic Crisis.- Evolutionary Consequences of Mass Extinctions.- The Neontologico-Paleontological Interface of Community Evolution: How Do the Pieces in the Kaleidoscopic Biosphere Move? Group Report.- What Is a Community?.- Evolution and Coevolution in Communities.- Large-scale Changes in Animal and Plant Terrestrial Communities.- Phanerozoic Marine Communities.- Appendix: Geological Time Scales.- List of Participants with Fields of Research.- Author Index.

Hypothesis testing is not a straightforward matter in the fossil record and here, too interactions with biology can be extremely profitable. Quite simply, predictions regarding long-term consequences of processes observed in liv­ ing organisms can be tested directly using paleontological data if those liv­ ing organisms have an adequate fossil record, thus avoiding the pitfalls of extrapolative approaches. We hope to see a burgeoning of this interactive effort in the coming years. Framing and testing of hypotheses in paleon­ tological subjects inevitably raises the problem of inferring process from pattern, and the consideration and elimination of a broad range of rival hy­ is an essential procedure here. In a historical science such as potheses paleontology, the problem often arises that the events that are of most in­ terest are unique in the history of life. For example, replication of the metazoan radiation at the beginning of the Cambrian is not feasible. How­ ever, decomposition of such problems into component hypotheses may at least in part alleviate this difficulty. For example, hypotheses built upon the role of species packing might be tested by comparing evolutionary dy­ namics (both morphological and taxonomic) during another global diversi­ fication, such as the biotic rebound from the end-Permian extinction, which removed perhaps 95% of the marine species (see Valentine, this volume). The subject of extinction, and mass extinction in particular, has become important in both paleobiology and biology.