The “DAWNDINOS” study combined evolutionary and biomechanical research that tested how the anatomy of extinct dinosaurs and their relatives (archosaurs; “ruling reptiles”) was related to their behaviour. We addressed the “locomotor superiority” hypothesis that early, bipedal dinosaurs evolved advantages in their locomotor performance over other Late Triassic archosaurs. This hypothesis was first proposed to explain what made dinosaurs distinct from other Triassic species, perhaps aiding their survival into the Jurassic period. However, the hypothesis remained untested or unfairly dismissed. We directly tested this question for the first time, and developed the best cutting-edge tools to do so.
Extant archosaurs (crocodiles and birds) allowed us to experimentally measure key factors (such as 3D skeletal motions and limb forces) that are involved in walking, running, jumping, standing up, and turning behaviours. We used biomechanical computer simulations to estimate how these behaviours were achieved, or whether more extreme behaviours (e.g. faster speeds) might still have been feasible but not observed. This refined our simulations by testing major assumptions, and validated them for studying extinct archosaurs. Additionally, we simulated extinct archosaurs, showing the diversity of behaviours they likely used.
In the final Period of the study, we used our simulation tools to predict how Triassic/early Jurassic archosaurs may have moved, and to compare how their performance in the behaviours related to locomotor traits, testing if the results fit expected patterns for “locomotor superiority.” Our results to date are not fully conclusive but do hint at some aspects of superior locomotor performance (e.g. running speed), offering some degree of support to the hypothesis that dinosaurs benefited from locomotor superiority over their contemporaries. We also have shown how bipedal locomotion evolved at least twice in extinct predecessors to crocodiles, but actual ancestors of crocodiles were unlikely to have ever been bipedal. Our new methods move the study of locomotion in extinct animals forward by “ground-truthing” those methods in studies of living animals and by establishing repeatable, transparent, openly accessible techniques for building and analysing digital models and simulations.
