Continental Ichnofossils as Climate-Indicator Proxies in Deep Geologic Time: Integrating Ichnology and paleopedology to Access Changes in Paleohydrology and Paleoclimate

Hasiotis, Stephen¹, Mary J. Kraus², Jon J. Smith³, John W. Counts³, Daniel Woody² (1) The University of Kansas, Lawrence, KS (2) University of Colorado, Boulder, CO (3) University of Kansas, Lawrence, KS

Continental ichnofossils produced by such organisms as crayfish, termites, ants, beetles, and soil bugs, can be very useful as climate-indicator proxies for interpreting paleoclimate in deep geologic time. Their interpretational value is strengthened when integrated with the paleopedogenic characteristics of the sediments in which they where emplaced. Their importance to interpreting deep-time paleoclimates is based on actualistic studies and the distribution of present-day biodiversity and soils, and how they record the climate characteristics.

Traces produced by terrestrial and freshwater organisms are an extension of each organism's phenotype, many of which are unique and diagnostic of a particular organism behavior. Traces produced by continental organisms are, therefore, indicators or hidden biodiversity since their body fossils are preserved rarely in well-oxygenated soils and subaqueous sediments. The type and abundance of biodiversity is used to interpret the climate type of the strata in which they are found.

Invertebrate and root-pattern behaviors, in particular, are sensitive to soil moisture levels and the position and fluctuation of the water table in the media in which they live. The groundwater profile, in turn, is controlled by the local hydrology and regional climate. Crayfish burrow depth and morphology is controlled by seasonal fluctuation and depth of the water table. The adults and nymphs or larvae of many soil bugs and beetle are sensitive to soil moisture levels in which they burrow and reproduce. Most burrow and survive in sediments with moisture levels between 7 and 37%; above or below they perish. The size, shape, depth, abundance, and distribution of ant and termite nests are also controlled by the groundwater profile.