REILLY, Stephen M.*; MCELROY, Eric J.; Ohio University; Ohio University: Tuataras and salamanders show that walking and running mechanics are ancient features of tetrapod locomotion

The slow lumbering locomotion of tuataras and salamanders represents the original form of quadrupedal locomotion employed by early terrestrial vertebrates. Studies of whole-body mechanics show they use the same walking and running mechanics known in fast moving (cursorial) animals. When walking, these sprawling animals saved energy via pendular mechanics as efficiently as many cursorial animals. However, unlike cursorial animals, tuataras and salamanders do not change gait (they always trot) or mechanics with speed. Thus, walking and running mechanics have been a feature of quadrupedal locomotion since the tetrapods emerged over 400 million years ago, but running was not originally adapted for increasing speed.