Scientists have long puzzled over why some dinosaurs had feathers and wings long before they evolved the ability of flight. Experiments with a robot dinosaur may now have revealed the answer – they used them for hunting.
Feathers show up in a range of dinosaur species, including icons like the velociraptor, but most of the time they were in a primitive form that would have only enabled the animals to hop short distances or glide at best. Only one group, known as Pennaraptora, sported plumage of pennaceous feathers, the same kind that still adorn modern birds today and allow them to fly.
The problem is, these feathers appeared in the fossil record long before their owners had strong enough wings to take to the skies. Evolution doesn’t just mess around with new features for fun, so what purpose did feathered proto-wings serve before the animals also realized they could use them to fly?
Researchers at Seoul National University had a hypothesis that these feathered dinosaurs might have used them to hunt their prey, in a way similar to some modern birds like the roadrunner. Contrary to popular belief, roadrunners don’t eat from piles of “Free Bird Seed” placed under suspiciously precarious boulders – they engage in a behavior called “flush-pursuit foraging,” where they flap their small wings and spread their tail feathers to spook insects out of hiding so they can catch them.
To find out if Pennaraptora dinosaurs could have done the same, the researchers built a robot called Robopteryx, modeled on a peacock-sized dinosaur called Caudipteryx. The team programmed Robopteryx to perform a few variations of flush-pursuit behaviors, including spreading its proto-wings and raising its tail.
Then, they took the robot out into the wild and tested whether those behaviors would work to spook insects. The chosen prey was grasshoppers, since they’re known to flee in response to flushing behavior in birds, and had relatives living at the same time as Caudipteryx.
Sure enough, the experiments showed that 93% of the grasshoppers fled when the proto-wings were flapped, while only 47% did without the wings. The grasshoppers also seemed to flee more often when the robot had feathers on its tail, or white patches on its wings.
These results suggest that some dinosaurs may have evolved these feathers and proto-wings to boost their hunting success. Over time, larger and more elaborate displays could have arisen, which eventually could have helped the animals evolve the power of flight. After all, a previous study using a robotic Caudipteryx found that the proto-wings flapped while the dinosaur ran.
The research was published in the journal Scientific Reports. The Robopteryx can be seen spooking a grasshopper in the video below.
Source: Seoul National University
