show Abstracthide AbstractThe case of Bootherium bombifrons is interesting for a number of reasons: this extinct genus shared much of its range with other ovibovines (it has been suggested that niche partitioning may have allowed their coexistence). In this study I have looked at two main questions: first, when did Bootherium and its extant sister taxon, Ovibos, diverge, and what were the environmental circumstances at the time? And second, what is the impact of locus choice on divergence estimates? I obtained sequence data from twelve individuals enough to assemble much of the mitogenome; three genes are used in these analyses: control region, cytochrome B, and cytochrome oxidase I.