Using Experimental Neoichnology and Quantitative Analyses to Improve the Interpretation of Continental Trace Fossils

摘要

The successful interpretation of continental ichnofossils is impeded by our limited knowledge of the burrows produced by modern continental animals. Actualistic studies of modern burrowing animals provide the data that make trace fossils invaluable to paleoecological and paleoenvironmental reconstructions. The goal of this project is to determine how well burrows produced by terrestrial arthropods, amphibians, and reptiles engaged in known behaviors under controlled environmental conditions can be differentiated on the basis of qualitative and quantitative morphology. The animals produced a diverse assemblage of shafts, tunnels, ramps, U-, J-, W-, Y-shaped and helical burrows, and mazeworks. The quantitative aspects of the burrow morphologies were compared using nonparametric similarity and distance indices as well as cluster analyses to determine if the burrow casts could be effectively differentiated based upon their tracemakers, behaviors, and environmental conditions. By using multiple properties of burrow morphology to compare the burrows statistically, many of the burrows were separated according to different behaviors and tracemakers, although overlaps did occur. Levels of similarity were highest amongst animals with similar morphologies, burrowing techniques, and behavioral patterns. Results from these analyses provide an assessment of our ability to reconstruct ancient soil ecosystems based on trace fossil morphology. By assembling a comprehensive analysis of the burrows of modern terrestrial animals, trace fossils may be described in a similar manner and compared directly to these modern analogs. This will be invaluable to improving the interpretation of tracemakers and behaviors.