The sand vipers of the genus Cerastes vertically burrow into the soft sand of the Saharan desert. The mechanics of vertical burrowing in Cerastes cerastes and Cerastes vipera were explored using a combination of morphology, videography, radiography, and experimental manipulation. The results suggest that the key to vertical burrowing is localized unilateral rib abduction. The ribs terminate in expanded calcified costal cartilages, which, when abducted, aid in scraping sand from below the snake and transporting it laterally. The transport of the sand is enhanced by long-axis torsion of the vertebral column. The specialized lateral scales of Cerastes do not appear to function in vertical burrowing.