The Evolution of Feathers on Dinosaurs
Feathers may have evolved on dinosaurs to frighten and flush out prey before they were used for flight, say researchers who built a winged robot and used it to scare grasshoppers.
Pennaceous feathers, which are the stiff, non-downy feathers with a central quill, are seen in fossils of some dinosaurs such as Caudipteryx, which lived about 124 million years ago. These dinosaurs had wings that weren’t strong enough for flight, so it is unclear how they were used.
Jinseok Park at Seoul National University, South Korea, and his colleagues hypothesised that they were used to startle prey into fleeing from hiding places, so they could be caught more easily. This “flush-pursuit” hunting strategy is used by modern birds including the greater roadrunner (Geococcyx californianus) and the northern mockingbird (Mimus polyglottos).
Robopteryx and its Effect on Grasshoppers
To test this idea, Park and his colleagues built a life-size robotic model of Caudipteryx, nicknamed Robopteryx. The robot approached grasshoppers, which were a likely prey of Caudipteryx, before flapping its wings. Without feathers, just under half of tested grasshoppers fled, but when the researchers attached feathers to the wings, this increased to over 90 per cent.
The team also recorded the neural responses of grasshoppers while they were shown an animation of Caudipteryx. Stronger activity was seen in neurons involved in escaping reactions when the feathers were present in the animation than without.
Park says the study demonstrates that flush-pursuit hunting was a potentially crucial factor in the evolution of pennaceous feathers on the arms and tails of dinosaurs.
The Role of Feathers in Hunting and Evolution
Predators with pennaceous feathers would have been able to flush out prey from further away, enabling them to see the trajectory of escaping creatures. This, in turn, would allow them to catch prey in the air relatively easily. Even if their target landed in vegetation, the predator could see where it landed and follow.
“We believe that pennaceous feathers evolved first for flush pursuing and were used later for flight,” says Park.
Rebuttal by Steven Salisbury
Steven Salisbury at the University of Queensland, Australia, says that the explanation for the evolution of pennaceous feathers to scare prey might be too simplistic. He believes that a structure as complex as a pennaceous feather would not evolve for such a specific behavioral role. According to Salisbury, feathers may have multiple functions such as insulating and incubating eggs, facilitating display and powered flight, and stabilizing body position when running.
There is probably no single reason why feathers evolved, says Salisbury. “You can have feathers to scare grasshoppers and you can have them to insulate and incubate eggs. They’re good for display, the stabilization of body position when running and, of course, for gliding and powered flight. Feathers help for all sorts of things.”
While the debate continues about the evolutionary reasons behind the development of feathers on dinosaurs, the research and hypotheses presented in this study shed light on the potential role of feathers in ancient predator-prey relationships.
In a groundbreaking study, scientists used robotic dinosaurs to investigate how feathers may have helped dinosaurs scare their prey. By equipping the robotic dinosaurs with feathered structures, the researchers found that the movement of the feathers created an intimidating display. This suggests that feathers may have evolved in dinosaurs not just for insulation or flight, but also as a way to visually intimidate and scare off potential predators or prey. This discovery challenges previous assumptions about the purpose of feathers in dinosaurs and raises new questions about the evolution of these fascinating creatures.
The robot experiment also revealed that the presence of feathers on dinosaurs may have served as a way for them to appear more human-like. The researchers found that the feathered dinosaurs attracted more attention from their prey and appeared more relatable, possibly making it easier for them to approach their prey unnoticed. The ability of feathers to make dinosaurs look more human-like may have given them an evolutionary advantage in hunting and survival. This suggests that the development of feathers in dinosaurs was not just for physical protection, but also played a crucial role in their social interactions and behaviors.