Abstract
AbstractHumans and birds utilize very different running styles. Unlike humans, birds adopt “grounded running” at intermediate speeds – a running gait where at least one foot is always in contact with the ground. Avian grounded running is paradoxical: animals tend to minimize locomotor energy expenditure, but birds prefer grounded running despite incurring higher energy costs. Using predictive gait simulations of the emu (Dromaius novaehollandiae), we resolve this paradox by demonstrating that grounded running represents an energetic optimum for birds. Our virtual experiments decoupled biomechanically relevant anatomical features that cannot be isolated in a real bird. The avian body plan prevents (near) vertical leg postures while running, making the running style used by humans impossible. Under this anatomical constraint, grounded running is optimal if the muscles produce the highest forces in crouched postures, as is true in most birds. Anatomical similarities between birds and non-avian dinosaurs suggest that, as a behavior, avian grounded running first evolved within non-avian theropods.
Publisher
Cold Spring Harbor Laboratory
Reference87 articles.
1. R. M. Alexander, Principles of Animal Locomotion (Princeton University Press, Princeton NJ, 2006).
2. Gait and the energetics of locomotion in horses
3. Energetics and mechanics of terrestrial locomotion;I. Metabolic energy consumption as a function of speed and body size in birds and mammals. J. Exp. Biol,1982
4. Energetics of running: a new perspective
5. Gait selection in the ostrich: mechanical and metabolic characteristics of walking and running with and without an aerial phase