If the wings arrived before the flight, what were they for?

Flight may be one of evolution’s most iconic innovations, but zoologist Piotr Jablonski is convinced that the first wings were primarily intended to be seen, not to fly.

The idea came to Jablonski after studying bird behavior in the American West. He noticed that some birds spread their wings or fanned out their tail feathers to attract insects into the open air. Then the birds would catch and eat the insects. If the first winged dinosaurs were the ancestors of birds, perhaps dinosaurs did the same, he thought.

For years, Jablonski and his colleagues have been putting this idea to the test, showing robotic, computer-simulated dinosaurs to real insects and recording their brain activity. The approach may seem unconventional, but the team is part of a growing group of scientists who want to experimentally reconstruct what remains elusive: the behavior of long-extinct animals.

In the experiments, Jablonski, now at the Museum and Institute of Zoology of the Polish Academy of Sciences in Warsaw, and his colleagues focused on small feathered dinosaurs called pennaraptorans. It’s unlikely that the animals’ protowings enabled flight, says Minyoung Son, a vertebrate paleontologist at the University of Minnesota in Minneapolis.

The wing surface area, he says, would have been too small to create the aerodynamic force needed to lift the pennaraptorans off the ground, and the span of their wing joints would also have limited their movements. Additionally, Son says, feathers must have an asymmetrical shape to be aerodynamic, and based on the fossil record, these dinosaurs “didn’t have aerodynamic feathers yet.”

To test prehistoric hunting tactics, Jablonski, Son and their colleagues first built a robot dinosaur. They modeled it after the size of a turkey Caudipteryxwhich is one of the best preserved “winged” pennaraptorans. The team added removable wings to the robot’s arms to test the insects’ responses to arms alone or arms with wings.

Once the robot named Robopteryx was finished, Jinseok Park took it on a paved path through a natural area in Seoul, South Korea, where he was able to encounter wild grasshoppers (The Infernal Oedal). The robot would confront the grasshoppers with what scientists call “flush displays,” opening its wings to the sides or swinging toward the insect and catapulting its tail forward. Over the course of hundreds of exposures over two summers, Park, an ornithologist now at the Max Planck Institute for Biological Intelligence in Planegg, Germany, compared how often grasshoppers would flee from Robopteryx, with and without its protowings. THE flush displays were more effective with protowingsaccording to the results of the study published in Scientific reports in 2024.

But researchers were still curious about different styles of flush screens with different types of projection movements. Instead of building another robot, the researchers chose to animate a Caudipteryx and show it to the insects on a computer screen. This time, the team focused on domesticated locusts and their neural responses to movements that lead to flight.

The procedure was invasive. Park clipped an electrode to each locust’s nerve cord while pinning another to its abdomen. The electrodes were then connected to a specialized instrument that detected and recorded neuronal activity. THE visual displays were more effective at eliciting a neural response from insects when the animation Caudipteryx had protowingsinstead of just bare forelimbs, the team reports in a paper published April 7 on bioRxiv.

Although there isn’t yet enough information about pennaraptorans to conclude that their protowings were in fact used for flush displays, “what this shows, quite elegantly and convincingly, is that it’s possible,” says paleontologist Corwin Sullivan of the University of Alberta in Edmonton, Canada.

And that’s not all. “Let’s say the first pennaraptoran feathers were used for these flush displays,” says Sullivan. “That doesn’t mean they couldn’t have been used for other purposes.” Jablonski agrees. He and Sullivan suggest that dinosaurs might also have waved their wings at potential mates.