Backfilled Meniscate Burrows in Lower Permian (Wolfcampian) Paleosols, Council Grove Group, Western Kansas

Paleosols in core from the Lower Permian (Wolfcampian) of western Kansas reveal an assemblage of previously undescribed meniscate backfilled burrows. Burrows are similar, but not identical, to Naktodemasis bowni Smith et al. 2007, which are composed of variably thick packets of fine, slightly to strongly asymmetrical backfill meniscae with a diameter that narrows and widens along the path of the burrow. The Permian meniscate backfilled burrows differ from other ichnogenera of meniscate backfilled burrows by its tightly spaced, slightly asymmetrical, texturally homogeneous, packeted menisci, its lack of a constructed lining, and consistent diameter. The Permian meniscate backfilled burrows are distinguished from N. bowni by differences in packeting of menisci—packets in the Permian burrows are mostly not offset from adjacent packets and are more variable in size than N. bowni. Trace-fossil assemblages in the type locality are monospecific and highly abundant and co-occur with rhizoliths. Although Lower Permian strata in this area consist of both marine and continental deposits, the backfilled meniscate burrows are found in incipient to well-developed paleosols; however, they are less visible in well-developed paleosols. The burrows are visible in paleosols due to differential redoximorphic coloration between burrows and ambient sediment, and were likely formed in a subaerial environment with a fluctuating water table. Due to similarities with traces made by extant species of beetles, we hypothesize that the Permian trace fossils are the result of the feeding and locomotion activities of arthropod insect larvae similar to that of scrabaeid beetles. Given the environmental tolerances of modern beetle larvae, the presence of such trace fossils indicates a narrow range of soil moisture conditions and the presence of adequate vegetation as a food source. These results are consistent with previous hypotheses of the Early Permian in North American as dominated by a monsoonal climate with moderate precipitation.