Exploring the accuracy of palaeobiological modelling procedures in forward-dynamics simulations of maximum-effort vertical jumping.

The body fossil record cannot preserve the dynamics of animal locomotion, and the only way to systematically reconstruct it is through simulation. However, musculoskeletal models used in simulation studies are typically simplified, meaning that their efficacy must first be demonstrated on living animals. Here, we evaluate a workflow for forward-dynamics simulations of maximum-effort vertical jumping, using simplified human and guineafowl models built with muscle masses from either measured data or estimated with methods previously applied to fossils. Predicted human performance was approximately 10% below experimental averages when known muscle masses were used, while the error ranged between +3 and -10% with palaeobiological methods. The simulations also correctly replicated the kinematic strategies (countermovement or squat jump) used across different starting postures. In contrast, predicted guineafowl performance was around 50-60% experimental values, irrespective of reconstruction method. Guineafowl model underperformance likely reflects simplifications related to foot mobility, muscle activation speeds and muscle fibre lengths, with the latter potentially being adaptively important to exceptional avian jumping performance. These findings emphasize that current muscle reconstruction and simulation approaches are most suited for evolutionary analyses where broad changes in body morphology and posture may significantly impact vertical jumping through pronounced qualitative differences in kinematic strategy.