The Adaptive Significance of Tetrapod Gait Selection

Abstract

At the slow walk tetrapods avoid lateral couplets gaits to minimize support by ipsilateral bipods. Most of them use the lateral sequence because tripods then make larger triangles than for the diagonal sequence. Of the running symmetrical gaits the single foots (in each sequence) permit the smoothest and fastest travel without suspensions. The trot and pace allow two legs to thrust in unison, the former giving the most stability to animals not placing the feet well under the body and the latter avoiding interference for long legged runners. The bound and half bound are most used by small agile mammals for bursts of speed and for maneuvering on rough terrain by a series of leaps. Such animals use the extended suspension. Large cursors on open terrain usually select the shorter more economical, gathered suspension. The fastest runners use both suspensions to gain long strides. At moderate speed the transverse gallop has the advantages over the rotary gallop that both bipods and tripods are more stable and that interference may be avoided. At high speed using both suspensions, none of these advantages pertains. The rotary gallop may then increase maneuverability.