EXTREME CROCS · EXploration of TerREstrial Mobility and Ecology in Crocodylomorphs

Fully understanding the ecology and evolution of extinct species requires analysis of their locomotor abilities, which are interactions with their environment that correlate with the morphology of the postcranial skeleton in complex ways. Locomotor abilities provide valuable insights into potential behaviors and ecological roles, such as how species hunted, avoided predators, selected habitats, and found mates. Crocodylomorpha, which nowadays comprises only 28 species of semi-aquatic ambush predators namely crocodylians is an important group for studying ecology and the processes of evolution over Deep Time, since Crocodylomorpha colonized a variety of environments and displayed a wide range of sizes and shapes for over 200 My. The aquatic clades Dyrosauroidea and Thalattosuchia, two notable examples of this rich diversity, exhibit clearly dissimilar anatomy, especially compared to modern crocodylians, implying strongly divergent locomotor abilities and behaviors, notably an inferior range of terrestrial gait. This divergence allows for functional hypotheses to be tested; hereby I hypothesize that habitat has a strong impact on the morphology of the crocodylomorph skeleton, which can be used as a basis to infer habitat on the scale of Crocodylomorpha (through quantitative proxies). As such, the primary goals of EXTREME CROCS are to use computational biomechanics, joint mobility analyses, and geometric morphometrics on entire skeletons to assess biomechanical form and function in extinct Crocodylomorpha and explore how the morphology of the appendicular skeleton is linked to terrestrial and swimming locomotor abilities. I will produce 3D musculoskeletal whole-body models of six species and use these to compute predictive simulations of optimal locomotor performances. These simulations will unveil the ranges of possible terrestrial behaviours (e.g. sprawling, high-walk, galloping), while intervertebral and limb joint mobilities will attest swimming abilities.