Role of Lateral Body Bending in Crocodylian Track Making

Locomotion in the alligatorids Caiman and Alligator show ontogenetic changes in gait width, manus orientation, and the amount of lateral body movement. In addition, the trackway of an adult Caiman is narrower than predicted for a semierect position of the limbs based on stance. The narrowness of the Caiman trackway is due to lateral movement of the body during locomotion. This movement allows placement of the feet closer to the trackway midline than would occur if no lateral bending occurred. Lateral movement is widespread among limbed tetrapods, yet little consideration has been given to its effects in trackmaking. Inferring stance from fossil trackways must take into account lateral body movement, otherwise the resultant hypothesis will be flawed.