The specimen hails from the Hell Creek Formation of northeastern Montana, U.S.A. The exact location of ‘Barbara’s’ discovery is lands located in Township 14 North, Range 36 East MPM in Garfield County, Montana, USA.
This geological formation comprises sandstones, siltstones, claystone, and mudstones from ancient rivers, peat bogs, and floodplains that formed in the riverine environment (Clemens and Hartman, 2014; Nudds and Selden, 2008) during the Late Cretaceous (Maastrichtian). Although other dinosaurs are found in the Hell Creek, the formation is best known as the discovery location for the holotype, or name-holder, of Tyrannosaurus rex. Moreover, because of recent discoveries, it is now known as the richest area for T. rex discoveries (Horner 2011, Marshall 2021).