Population sizes of Tyrannosaurus rex cannot be precisely estimated

Marshall et al. recently estimated population densities, range sizes, instant and cumulative total population sizes for Tyrannosaurus rex with narrow ranges of uncertainly. I revisit the assumptions that led them to these conclusions and show that many of these parameters are associated with much wider margins of error than they estimated. Biogeographic estimates seem to have been especially unrealistic, seriously hampering the effort to calculate population level parameters. I posit that biogeographic and ecological uncertainties make it extremely unlikely to be able to estimate population sizes of long-extinct species.