Abstract Trace fossils are difficult to identify and classify phyllogenetically but can be assigned relatively easily to various behavioral, perservational, and environmental categories. Analysis of these aspects of trace fossils, in turn, can yield information that is invaluable in sedimentary geology. The most significant contributions of trace fossils have been in paleoecology, sedimentology, and environmental reconstruction, including recognition of local and regional-temporal facies changes, patterns of bioturbation, and documentation of individual paleoecological parameters. Trace fossils are potential indicators of bathymetry, currents, food supplies, aeration, rate of deposition, depositional history, substrate stability, and salinity. They are emerging as useful tools in the developing fields of sequence stratigraphy, allostratigraphy, and event stratigraphy.