Zoophysics of the evolution of terrestrial locomotion

While the morphologies of transitional species are poorly known, what is certain is that the physics of supporting body weight and walking on four limbs is the same for all vertebrates. Although research has addressed morphology of both fossil and extant fishes and early tetrapods, few studies have endeavored to determine the functional requirements necessary for a fish to walk on land. In addition, research on the evolution of appendicular morphology has focused primarily on the distal limb components and not on the pectoral and pelvic girdles that are responsible for supporting the weight of the body over the limbs. The work below is an effort to create a model for predicting the phenotypic characteristics of an organism given its genomic and performance-selective conditions.

We learned that many hillstream loaches use a tetrapod gait on land

Crawford et al. 2022. They like to move it (move it): Walking kinematics of balitorid loaches of western Thailand. Journal of Experimental BIology. doi:10.1242/jeb.242906

We discovered a rare fish that has tetrapod-like morphology and locomotion

Flammang et al. 2016. Scientific Reports 6:23711. PDF, Supplementary Video 1, Supplementary Video 2, Supplementary Video 3, Interactive Model

We found 3 morphotypes among walking hillstream loaches.

Crawford et al. 2020. Skeletal and muscular pelvic morphology of Hillstream Loaches (Cypriniformes: Balitoridae). Journal of Morphology. dx.doi.org/10.1002/jmor.21247

We are using biomechanics and robotics to investigate the evolution of terrestrial locomotion

NSF Understanding Rules of Life RAISE: “A Phylogenomically-Based Bioinspired Robotic Model Approach to Addressing the Evolution of Terrestrial Locomotion”