Atlatl saltation: A new model for richochetal locomotion

Small mammal saltatorial adaptations maximize escape in patchy environments where sudden positional changes are more effective than dashing away in one direction. Saltation is an independent series of longer jumps than body size predicts; saltators alter trajectory midleap using tails as rudders. Although from species differing in biogeographic range, phylogenetic origin and appearance in the fossil record, their ecological niches constrain saltators to show common morphologies. These include bipedal hopping, long, tufted tails, large eyes and auditory bullae, elongated feet and hind limbs with proximal muscle bellies. This study examines saltatory adaptations among forms of common appearance by comparing saltation to the atlatl, a device for increased human hunting efficiency that propels projectiles farther and more accurately. Such animals are atlatl saltators. The body parts determining these locomotor capabilities compare to those of an atlatl, but are analogous only when it is inverted. The atlatl saltator foot corresponds to the atlatl projectile and launcher, the calcaneus to the atlatl spur and the lower leg to the atlatl handle. The knee corresponds to the human wrist holding the device. Knee straightening equates to a forward wrist snap. In parallel, the animal uses large thigh muscles to move forward, while the human movement allows large trunk muscles to effect a corresponding atlatl movement.