The origin of tetrapods and terrestrial locomotion involved the transformation of small pelvic fins into large weight-supporting hind limbs. The closest fossil relatives of tetrapods are the elpistost
OpenSim v4.1 musculoskeletal model and geometry files from:Lecuona, A., Keeble, E., Lin, Y., Hutchinson, J.R. 2025. Hindlimb functional morphology and locomotor biomechanics of the small Late Triassic
