A phytosaurian trackmaker would imply that the common ancestor of pseudosuchians, and therefore archosaurs could approximate the high walk (depending on phylogeny), and if so, erect stance and parasagittal gait did not evolve independently in pseudosuchians and ornithosuchians, although the kinematic mechanisms differed in the two groups. Moreover, the trackmaker was performing the high walk. We show that the Triassic trackway Apatopus best fits the anatomy and proportions of phytosaurs, based on a new reconstruction of their foot skeleton it is less likely to have been made by another pseudosuchian or non-archosaurian archosauromorph. gait so as not to entail different processes: ‘sprawling’ and ‘erect’ should refer to continua of stance ‘rotatory’ and ‘parasagittal’ are more appropriate ends of a continuum that describes the motions of gait. We suggest a further separation of terminology related to stance vs. erect posture, has been replaced by a subtler understanding of a continuum of changing limb joint angles. The classic paradigm for the evolution of stance and gait in archosaurs, a three-stage transition from sprawling to ‘semi-erect’ to. For some decades, a major focus of research has been on how locomotor modes changed in some archosaurian reptiles from a more or less ‘sprawling’ to an ‘erect’ posture, whether there were discrete intermediate stages, and how many times ‘erect’ posture evolved.
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