BIOTIC DESTRUCTION OF TERRESTRIAL PLANT DEBRIS IN THE LATE PALEOZOIC MARINE-ENVIRONMENT

Small, oblong, limonitized coprolites (<0.5 mm) containing macerated t errestrial plant debris have been recovered in Westphalian and Stephan ian (Upper Pennsylvanian) gray to black shales that were deposited in dysoxic outer-shelf marine environments. The internal structure and ex ternal surfaces of the coprolites are unlike those of vertebrate copro lites and unlike ejecta recovered in stratigraphically adjacent anoxic sediments. Stratigraphically adjacent oxygenated sediments have been homogenized by numerous kinds of mobile benthic invertebrates, whose a ctivities have probably destroyed any trace of plant-bearing coprolite s in the more nearshore environments. Coprolites of terrestrial origin that contain plant debris are considered to have been generally too l oosely consolidated to survive long-distance transport from lens to pe rhaps several hundred kilometers from land. Thus, the coprolites in th is report appear to represent a feeding pattern, by one or more kinds of marine macroinvertebrates, on drifted land-plant debris that sank i nto offshore marine environments. Distribution of such plant destructi on represents a previously undocumented taphonomic pathway, demonstrat ing an unsuspected plant-animal interaction for terrestrial macroscopi c plant debris in Upper Paleozoic marine environments.