19.2 Wednesday, Jan. 4 Tracking Reptilian Footprints BURNELL, Amy L*; YOUNG, Bruce A; Univ. of Massachusetts, Lowell; Univ. of Massachusetts, Lowell email@example.com
The few previous controlled studies on the influence of substrate on tetrapod locomotion have shown significant changes in locomotor cycles with changing substrate. We examined the relationship between substrate and the locomotion of a large sprawling lizard, the water monitor (Varanus salvator). Sub-adult to adult animals (lengths> 1.5meters) were initially filmed walking over a force plate. In subsequent experiments the animals were filmed locomoting over substrates of varying degrees of compactness (loose sand, compact sand, saturated sand, and submerged sand). For the trials over the substrate, dental stone was used to take impression of footprints; the casts were then digitized with a 3-D scanner and aspects of each footprint quantified using ImageJ. High-speed digital videography of individual footfalls on each substrate allowed quantification of both deformation of the foot as well as foot-substrate interactions (e.g., slippage, substrate ejection). Statistical analyses of the locomotor velocity and duty cycles, quantitative features of the footprints, and the foot-substrate interactions revealed significant differences by substrate type.