Escape behaviors in prey might have underlain the evolution of pennaceous plumage in predatory dinosaurs

Abstract

Numerous non-avian dinosaurs possessed pennaceous plumage in the proto-wing and tail1, whose function remains unclear. We hypothesize that they might have been used during hunting that resembles avian flush-pursuers, who use wing/tail displays to flush hidden prey and pursue it2,3. Using a dinosaur robot, we confirmed that efficiency in flushing grasshoppers by moving forelimbs and tail increased when proto-wings were present, especially distally and with contrasting pattern, and when caudal plumage (tail feathers), especially of large surface, was present. Responses of grasshopper escape neurons to animations of distal proto-wing displays matched the observed escape behavior. Hence, the surface of stiff pennaceous feathers might have evolved to exploit the sensitivity of prey escape pathways and to help dinosaurs aerodynamically in quick maneuvers during pursuits after prey.