GREAT BASIN BISON LATIFRONS: STABLE ISOTOPE PALEOECOLOGY

This study addresses the distribution of Bison latifrons throughout the Late Pleistocene of North America, examines its diet, and determines whether the species migrated long distances. These animals likely competed directly and indirectly for resources with other megafaunal species, such as Mammut americanum and Bison antiquus, and a more robust understanding of their paleoecology has implications for further studies of their interactions.

Bison latifronsis an enigmatic Late Pleistocene megaherbivore. Previous researchers interpret this taxon to have lived in forest openings and woodlands taking advantage of high browse and woody plants as food. Little stable isotopic work has been focused on this taxon to confirm the previous interpretation and no isotopic studies have been conducted on high altitude populations. This study aims to address both of these issues.

B. latifrons occurs in California, Idaho, Nevada, Colorado, and Florida among others. Using carbon and oxygen stable isotopic analyses I hope to see if there is some sort of migration pattern in the signatures or perhaps a signature which represents a local population. Samples have thus far been collected from the Snowmass, Colorado site of Sangamon age, the Panaca, Nevada site of Rancholabrean land mammal age, and the American Falls Fm of Idaho representing the Illinoian. Carbon and oxygen stable isotopic data should shed light on the distribution of isotopic values across the taxon’s temporal and physical range. Unfortunately the Snowmass samples were inconclusive and potentially diagenetic, and resampling must be conducted to verify. Previous research on the Panaca samples yields δ¹³C values indicating a mixed diet of C₃ and C₄ plants, while δ¹⁸O values agree with those expected of the mortality site.

Oxygen isotopic data should positively correlate with the locations of the sampled individuals, helping to determine their origins. Oxygen isotopic data with δ¹⁸O values offset from those of the mortality site indicate a herd with origins elsewhere. Carbon isotopic values in bison tooth enamel are offset by about -12‰ through biomineralization. δ¹³C values of approximately -15‰ indicate the animals consumed mainly C₃ browse. Any significantly offset δ¹³C values indicate an individual that ate a mixed diet of C₃ and C₄ plants.