Comparison between the sequential animation of the landing sequence and a normal walking sequence. (a) The landing sequence, based on the landing track CR01.02, Lower Tithonian, Crayssac, France. Phase 1 corresponds to the first set of pedal tracks, which reflects bipedal terrestrial contact. Phase 2 corresponds to the pause of the animal after landing, with
all four limbs on the ground, transversely parallel to each other. The distance between ipsilateral pes and manus is very short, and the body is erect. Phase 3 corresponds to the first walking sequence, as the animal arranges its limbs in preparation for normal terrestrial progression. The distance between manus and pedes increases and the body acquires a subhorizontal position. Phase 4 corresponds to the start of normal terrestrial progression. (b) The walking sequence, based on the typical terrestrial trackway CR96.22, Lower Tithonian, Crayssac, France. Note
that the manus prints are posterior to the pes prints, the mediolateral distance between the pedes is shorter and the pace length is longer than in the landing track. Scale bars, 10 cm. RP, right pes print; LP, left pes print; RM, right manus print; LM, left manus print. The numbers correspond to the discussion in the text. From Mazin et al. 2009.