There is great interest in calculating accurate values for Earth’s palaeogravity. One fundamental techniqueto quantify palaeogravity is to compute weight against mass estimates of ancient animals. This technique isapplied to four specimens of Tyrannosaurus rex, representing some of the most complete theropod dinosaurskeletons known. For the Tyrannosaurus rex specimens "Carnegie" CMNH 9380, “Wankel rex” MOR 555,"Stan" BHI 3033 and "Sue" FMNH PR 2081, the results indicate that palaeogravities of 0.67g, 0.66g, 0.61g,and 0.64g ± 20% respectively are reliable estimates for 67 Ma.