Figure 3 in Tyrannosaurus was not a fast runner

Figure 3 Estimated extensor muscle mass (T, as a percentage of body mass per leg) required to run quickly. Data are from various models and extant species plotted against log(mbody) to illustrate the scaling of T. Larger runners need a larger fraction of their body allocated to extensor muscle mass.Three shades of grey indicate the likelihood of running ability, based on estimated T. Very low estimated T implies a good chance of being a capable runner. Very high estimated T signals little chance of being a capable runner. Intermediate values of estimated T are inconclusive, and running ability in this case depends on the ratio of actual extensor muscle mass to T. Values of T greater than 50% per leg, or greater than 100% in total, are impossible.The solid line represents the case of scaling a chicken isometrically up to 6,000 kg.