Like the ilium, the ischium is another bone which is distinctive in "Prestosuchus". It is thicker than the pubis and makes a larger contribution to the acetabulum. Prominent crests are developed along the dorsal (upper) and ventral (lower) edges of the ischium. A large midline ventral crest is only seen in "P. chiniquensis", "P. nyassicus", and "Batrachotomus" among loricatans. However, "Batrachotomus"'s crest smoothly transitions from the base of the ischium to the shaft, whereas an abrupt angled incision is observed in this area for "P. chiniquensis" and "P. nyassicus". The paired dorsal ridges are autapomorphies of "Prestosuchus," though they extend further down the shaft in "P. chiniquensis" than "P. nyassicus". They are edged by long depressions and separated by a shallow groove on the midline of the ischium, where the left and right ischia have fused. As with other loricatans, the tip of the ischial shaft is slightly expanded into an ischial boot.