NEOICHNOLOGY OF BISON: IMPLICATIONS FOR (PALEO-) ZOOGEOMORPHOLOGY OF SAND-DOMINATED LANDSCAPES

Bison (Bison spp.) are recognized for their impact on ecosystems as a keystone species, however, only a handful of studies, most dating back to the 20^th century, have focused on their geomorphological impact. These massive ungulates have the greatest zoogeomorphic yield due to the highest foot loading pressure of any extant land mammal (1000 -1300 g/cm²). Changes in bison population in North America and Europe are well documented, with populations rebounding following mega-fauna hunting and historic near extirpation (pre-European numbers estimated at >40 million), with current global population of >0.5 million (20,000 in the wild). Bison produce a diverse suite of traces including wallow pits, trails, trackways/trample grounds, rock rubs, tree hornings, mineral (salt) licks, and bio-deposition (coprolites and advected sediment). In the sedimentary record, ungulate tracks attributed to bison (where bedding-plane view of elite tracks and undertracks is available) are assigned to Bijugopeda anterofossa (McNeil, 2007), however the original ichnogenus Pecoripeda of the Vialov (1965) ichnotaxonomic nomenclature should be considered for suspected tracks, especially when studied in cross-section. Billions of bison racks are preserved in sand dominated substrates throughout the world, including diverse aeolian settings and outwash plains. Ongoing research addresses the importance of moisture content, temperature extremes (e.g., freezing), and mineralogical anomalies (heavy-mineral concentrations) in the formation and taphonomic history of large ungulate hoofprints, with the goal of refining and quantifying the paleoenvironmental conditions favorable for track preservation and recognition. We evaluate the feasibility of identifying and characterizing both simulated (indenter-generated) and actual (field-based) tracks using low-field magnetic susceptibility and high-frequency (800-2300 MHz) georadar imaging. Ultimately, this research will help to constrain sediment properties during track formation and establish diagnostic criteria for reconstructing their past distribution and their role as key zoogeomorphic agents.