Grasshoppers in South Korea may be on high alert, after scientists created a robotic version of an enemy from the insects’ distant past. In a series of experiments, researchers scared grasshoppers using a robo-dinosaur with training wheels and flapping wings. The findings suggest early dinosaurs evolved their tiny wings not to fly, but to flush out hidden prey, the team argues in a paper published last week in the journal Scientific Reports.
The unlikely predator, named “Robopteryx,” is the modern reboot of Caudipteryx, a three-foot-long omnivorous dinosaur that lived in present-day China more than 124 million years ago. Scientists at Seoul National University in South Korea thought the best way to study Caudipteryx’s behavior was to bring it, somewhat, back to life.
Researchers attached nine motors to a model based on the species’ fossils, and they strapped on wheels for stealth. With the robotic dinosaur at the ready, the team prepared to probe the question: Just how, exactly, did early birds get their wings?
Known to eat grasshoppers and other bugs, Caudipteryx is thought to have largely resembled an ostrich, save for a pair of wings that looked several sizes too small for its body. These odd appendages certainly didn’t allow the dinosaurs to fly, and their tiny size hardly seemed to offer any utility.
“We are trying to get at ‘What’s the use of half a wing?’” Minyoung Son, a paleontologist at the University of Minnesota, tells Scientific American’s Meghan Bartels. “A full-size wing that could at least glide would make sense. But we have this fossil evidence for dinosaurs with what we would call half a wing.”
The first feathers that dinosaurs evolved appeared as mere hair-like bristles, reports the New York Times’ Asher Elbein. In fact, most dinosaurs with feathers used them only to keep warm, or to display different colors. Very few early species with wings actually used them to soar.
Among a number of theories—that wings helped dinosaurs balance, allowed them to jump higher, warmed nests of eggs or were simply for dominant show—the scientists wanted to test a prevailing hypothesis related to food. Today, some birds—which are modern dinosaurs—use their wings to scatter hidden insects and hunt them more easily.
“It’s been shown that the larger the wing display, the more insects the birds are catching and bringing to the nest,” study co-author Piotr Jablonski, an ornithologist at Seoul National University, tells the New York Times. “And of course, if you see it in birds, you think about dinosaurs.”
Robopteryx was engineered to mimic flush-pursuit hunting, a technique in which the predator enters an area where insects may be and flaps its wings to startle the creatures into giving up their hiding spots. With the prey exposed, the predator gives chase.
If the hunting method was successful, the team says, it may have prompted the evolution of larger, more feathered wings in dinosaurs. A plumage-free version of Robopteryx could only scatter less than half of the grasshoppers in the study area. But with wings, 93 percent of the bugs took off. And when the team added striped tail feathers to the robot, more of the insects were startled.
They also showed, in a laboratory setting, that the grasshoppers’ neurons indicated fear when confronted with animations of Robopteryx flapping its wings, compared to other imagery.
Notably, the scientists’ results were rejected by 11 journals before being published in Scientific Reports, and some paleontologists are skeptical of their thinking.
“I’m not so sure about this idea,” Michael Benton, a vertebrate paleontologist at the University of Bristol who was not involved in the research, tells the Guardian’s Ian Sample. “They are right that flight-type feathers originated in dinosaurs when they just had tiny wings that were too tiny for powered flight. However, these pennaceous feathers are very much adapted to make an unbroken wing surface, and the first feathered dinosaurs may have used them in gliding from spot to spot.”
“People often say ‘half a wing is no use’,” he adds, “but actually, half a wing is what many modern gliding lizards and mammals have, and it’s a great adaptation for non-powered flight.”
Whatever the reason for Caudipteryx’s wings, it will be hard for any scientists to back up their hypotheses with hard evidence. The robot experiment is “fun and compelling and even makes intuitive and rhetorical sense, but how do you prove it with fossils?” Steve Brusatte, a paleontologist at the University of Edinburgh who did not participate in the study, says to the New York Times.
It may be that wings did not specifically evolve for the purpose of flush-pursuit hunting, but the practice could have been one of many uses for the little appendages, researchers say.
“It captures the real complexity of form-function relationships in the natural world,” Julia Clarke, a paleontologist at the University of Texas who was not involved with the paper, tells the New York Times. “There is no reason ‘half a wing’ would need to have only one function.”