Fossorial gait patterns and performance of a shovel-headed amphisbaenian

Most studies on excavation behaviour of Amphisbaenia have been based on descriptive analysis through visual observation or external body motion records. Herein, we recorded the excavatory gaits of the shovel-headed amphisbaenid Leposternon microcephalum using videofluoroscopy. This technique films by X-ray emission, allowing a more detailed analysis of the amphisbaenid's underground locomotor behaviour and performance. Thus, we described, for the first time, its ascendant excavatory cycle and backward movement. Furthermore, we analysed its performance through the quantitative data (e.g. speed, travel distance, frequency, time) of each fossorial gait, including the three-step excavatory cycle previously described in the literature. When comparing the three-step and the four-step excavatory cycles, the first presented high average speed and short travel distances. Our original hypothesis that there was a relation between retreat/downward movement of the head and the intensity of burrowing activity was not corroborated by the regression analyses. This movement seems to be just a part of the motion needed to perform the excavatory cycle, not a propulsion step influencing burrowing activity. The results presented in this work contribute to a better understanding of L.microcephalum fossorial behaviour. Further studies can be performed to better describe and compare excavation patterns and performance among different amphisbaenian skull morphotypes (round headed, keel headed, shovel headed and spade headed).