Comments on “A tyrannosaur trackway at Glenrock, Lance Formation (Maastrichtian), Wyoming” (Smith et al., Cretaceous Research, v. 61, pp. 1-4, 2016)

The paper by Smith et al. (2016) included speed calculations performed from a tyrannosaur trackway at Glenrock, Lance Formation, Wyoming. These authors concluded that tyrannosaurs walked in speeds similar to those obtained for other large theropod, but faster than proposed for hadrosaurids, a potential prey. However, the calculations performed by Smith et al. (2016) suffered from methodological and computational errors, which greatly affected the reported results. Here I show that when speeds are correctly calculated from the Glenrock trackway, the obtained values are clearly (about 50-80 percent) higher than the wrong values quoted by these authors. This support even more a significant speed capability for tyrannosaurs than claimed by Smith et al. (2016).