FossilGaitSim: Exploring the Major Postural Transition in the Evolution from Synapsids to Mammals through Movement Simulations

• Applicant: Professorin Dr. Anne Koelewijn
• Subject Area: Automation, Mechatronics, Control Systems, Intelligent Technical Systems, Robotics ; Palaeontology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 558918908

We will investigate the evolutionary trajectory from sprawling, lizard-like, gait to cursorial, erect, gait in mammals and their ancestors using movement simulations and fossil trackways. We have selected five ichnotaxa, fossil records of movements, spanning from the early Permian to the Miocene, that cover the transition from sprawling to cursorial gait. We will investigate likely gaits and postures used to create these trackways, as well as the trackmaker’s morphometry, using movement simulations which are created by solving optimal control problems. The optimal control problem replicates the optimization that is solved by the central nervous system when planning and executing movements. Such simulations can successfully predict different human movements, by finding the movement that is most energy efficient. Similarly, we will explore optimal control problems as a tool to find the gait and posture used to create fossil trackway patterns. The dynamics model and its morphometric parameters (or parameter ranges) will be based on different information sources, from trackway measurements as well as from modern analogues and (incomplete) body fossils, if they are available. First, we will develop an adaptable full-body dynamics model that will be used to create the simulations. The adaptability ensures that different animals can be investigated by adapting the morphometric model parameters, which overcomes the limitation of current approaches, in which dynamics models of extinct animals are created from time-consuming scanning of body fossils. We will validate this model and our simulation approach using trackway and video data of extant animals, reptiles as basal relatives and mammals as derived relatives. Second, we will investigate the relationship between morphometry, gait, and posture. Using a sensitivity analysis, we aim to gain more insight into which morphometric parameters affect gait and posture, and especially the resulting trackway pattern. This analysis will inform us on the likely range of the morphometric parameters. We will also use phylogenetic trees and evolutionary optimization to explore the evolutionary trajectory of gait and morphometry using these simulations and the trackway information. Third, we will investigate the five selected trackways and find the likely gait and posture used to create them, as well as trackmaker morphometry, to explore the evolutionary trajectory from sprawling to cursorial gait. To do so, we will first gather and select trackways that are suitable for simulations for the five ichnotaxa, and then develop dynamics models based on different information source. Using these, we can create simulations and evaluate which gait and posture likely created these trackways.

• DFG Programme: Research Grants
• International Connection: Argentina
• Cooperation Partner: Dr. Verónica Krapovicas