FECAL-FILLED BORINGS IN A PSARONIUS ROOT MAT COAL BALL FROM THE MT. RORAH COAL BED

Coal balls are our primary source of information about Pennsylvanian tropical peat swamps, capturing the community composition and complex ecological interactions between terrestrial arthropods and plants. Borings (feeding holes), coprolites (fecal material), and other trace fossils from terrestrial arthropods commonly occur in coal balls and can be found in association with plant organs or distributed throughout the peat matrix. These trace fossils represent behavioral activities of once-living organisms. We report two borings from a singular coal ball originating from the Mt. Rorah coal member. Peels of the coal ball were made using the cellulose acetate peel method and digitized with an Axio Zoom V16. The borings range in size from 3 and 6 cm in length, separated by charcoalified woody tissue from Pennsyvanioxylon and Psaronius rootlets. The borings are filled with a mixture of uniform coprolites (ranging in size from 0.5-2 mm in diameter) and frass (<300 μm) occurring from coprophagy (feeding on fecal material). Both coprolites and frass are composed of plant material from Psaronious roots. None of the surrounding plant tissues show signs of herbivory. The context of the borings suggests that it was made by a detritivorous arthropod, potentially an insect within Blattoptera, boring through the surface peat layer. The presence of frass amongst coprolites containing similar material indicates secondary feeding by mites. The documentation of a burrow system offers a glimpse into the life history of the organism that produced these burrows, nutrient cycling, and captures an intermediate stage of coal ball formation.