Taphonomy and paleobiology

Taphonomy plays diverse roles in paleobiology. These include assessing samp le quality relevant to ecologic, biogeographic, and evolutionary questions, diagnosing the roles of Various taphonomic agents, processes and circumsta nces in generating the sedimentary and fossil records, and reconstructing t he dynamics of organic recycling over time as a part of Earth history. Majo r advances over the past 15 years have occurred in understanding (1) the co ntrols on preservation, especially the ecology and biogeochemistry of soft- tissue preservation, and the dominance of biological versus physical agents in the destruction of remains from all major taxonomic groups (plants, inv ertebrates, vertebrates); (2) scales of spatial and temporal resolution, pa rticularly the relatively minor role of out-of-habitat transport contrasted with the major effects of time-averaging; (3) quantitative compositional f idelity: that is, the degree to which different types of assemblages reflec t the species composition and abundance of source faunas and floras; and (4 ) large-scale variations through time in preservational regimes (megabiases ), caused by the evolution of new body-plans and behavioral capabilities, a nd by broad-scale changes in climate, tectonics, and geochemistry of Earth surface systems. Paleobiological questions regarding major trends in biodiv ersity, major extinctions and recoveries, timing of cladogenesis and rates of evolution, and the role of environmental forcing in evolution all entail issues appropriate for taphonomic analysis, and a wide range of strategies are being developed to minimize the impact of sample incompleteness and bi as. These include taphonomically robust metrics of paleontologic patterns, gap analysis, equalizing samples via rarefaction, inferences about preserva tion probability, isotaphonomic comparisons, taphonomic control taxa, and m odeling of artificial fossil assemblages based on modern analogues. All of this work is yielding a more quantitative assessment of both the positive a nd negative aspects of paleobiological samples. Comparisons and syntheses o f patterns across major groups and over a wider range of temporal and spati al scales present a challenging and exciting agenda for taphonomy in the co ming decades.