Fig. 5. Traces of landmark dots on the opening elytra of Prionus coriarius, subtended at different aspects in the external reference system. Open dots, left elytron; filled dots, right elytron. The side of the cube is 40 mm, bold ribs converge at the point (+20, +20, +20 mm). The 3-D graph can be tilted so that dots lie approximately along a straight line on either trajectory, or both trajectories are seen as arcs.