FIGURE 1 in How Fast Could Tyrannosaurus rex Run?

FIGURE 1. IN A FREE-BODY DIAGRAM for a running tyrannosaur, the angles of the leg joints (top) are critical parameters. In addi- tion to the forces and torques produced by leg muscles, external forces (bottom) including the weights of the body (Ƒb), thigh (Ƒt), shank (Ƒs), and metatarsus (Ƒm), as well as the ground reaction force (GRF) that acts a distance R from the toe joint must be incorporated. (Adapted from ref. 6.)