The Effect of Substrate Unevenness and Irregularity on Locomotor Performance and Kinematics of Curly-Tailed Lizards

Date of Award


Degree Type


Degree Name

Master of Science in Biology



Chief Instructor

Philip J. Bergmann

Second Reader

John A. Baker

Third Reader

Deborah L. Robertson


Uneven surfaces are ubiquitous in nature and animals must frequently move across them, yet their effects on locomotion are not well understood. I studied how surface unevenness and irregularity of substrates made of large particles affect the locomotor performance and kinematics of the terrestrial generalist sprinter, the Northern Curly-Tailed Lizard (Leiocephalus carinatus). I compared a flat surface (even), three sizes of spheres (regular but uneven surfaces), and three sizes of natural rocks (irregular and uneven surfaces). As the size of the particles increased, the unevenness of the surface increased. The lizards ran at similar speeds on all substrates, but compensated for different substrates with changes in kinematics. Substrate irregularity only affected hind limb retraction angle. Overall, I found that substrate unevenness affects kinematics but not performance and that unevenness matters more than irregularity.

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