Fig. 2. Schematic representation of two hypothetical functions of the lateral hypaxial muscles during locomotion (after Carrier, 1993). The first hypothesis is that the hypaxial muscles function to bend the body during swimming (A) and walking (B) through the synchronous action of the lateral and medial pairs of hypaxial musculature. A second hypothesis (C) is that the hypaxial muscles function to counteract long-axis torsion of the body during walking. The torsion hypothesis predicts that the lateral and medial pairs of hypaxial muscles will be active asynchronously on one side of the body during walking. Filled bars represent bursts of muscle activity recorded from the lateral and medial hypaxial muscle pairs on one side of the body. Darkened feet in (C) mark the limbs generating the torsional moments countered by the indicated muscle activity. *Denotes the side of the body with hypothetical muscle activity.