Study Indicates Early Wings Likely Served Non-Aerodynamic Functions

The Debate Over Wing Function in Early Dinosaurs

Scientists are divided over whether wings in early dinosaurs evolved mainly for flight or other purposes. A 2024 study in Scientific Reports suggests Caudipteryx dinosaurs may have used their ‘protowings’ to startle prey with sudden movements. But newer research complicates this idea, pointing to a more nuanced evolutionary path. This article looks at how wings in early dinosaurs and birds might have first served non-aerodynamic roles like thermoregulation, sexual display, or gliding, with powered flight developing later as an added benefit.

Background: The Evolutionary Puzzle of Wings

“The size and joint mobility of these wings make powered flight unlikely.”

Wings are one of evolution’s most remarkable innovations, yet their origins remain unclear. Insects were the first to develop wings, with fossil evidence showing they evolved from modified gills about 400 million years ago. These early wings likely helped with gliding or moving through dense plant life. Later, dinosaurs and birds developed feathered wings, raising questions about their original uses. A 2018 Nature study on Caudipteryx and Microraptor fossils found asymmetrical feathers, supporting the gliding theory. The Yi qi fossil, found in China, adds another layer, showing a unique wing structure with a rod-like bone that suggests a specialized gliding mechanism. These findings feed into the ongoing debate about whether wings evolved for gliding (arboreal hypothesis) or ground-based flapping (cursorial hypothesis).

Alternative Theories and Skepticism

While the Caudipteryx study offers strong support for hunting behavior, some experts caution against overreading the data. Minyoung Son, a vertebrate paleontologist at the University of Minnesota, says the ‘protowings’ of pennaraptoran dinosaurs were too small and structurally limited to create aerodynamic lift. ‘The size and joint mobility of these wings make powered flight unlikely,’ Son says. Plus, the asymmetrical feathers needed for flight appear to have evolved later, suggesting a slow shift from display to flight. This supports the broader debate over whether wings evolved for gliding or ground-based flapping.

Neural Responses to Wing Displays

The 2024 study by Jinseok Park and colleagues tested locust neural activity in response to animated Caudipteryx displays. Results showed protowings triggered stronger escape responses than bare forelimbs, backing up the idea that these structures could have startled prey. But the study’s methods have faced criticism. Paleontologist Corwin Sullivan of the University of Alberta calls the findings ‘elegant’ but stresses that ‘we can’t yet say these wings were used for hunting.’ He notes the same neural reactions could come from other stimuli, like sudden movements or color changes. This highlights the difficulty of inferring behavior from fossilized structures.

Wings in Non-Avian Species

The use of wings for purposes other than flight isn’t unique to dinosaurs. Modern Anolis lizards, for example, have wing-like skin flaps they use to glide between trees. These structures aren’t aerodynamically efficient but help with movement. Some fish species also have pectoral fins that aid in maneuvering through water. These examples show wings or wing-like structures can evolve for various functions before being adapted for powered flight. The Sinosauropteryx fossil, found in 1996, adds more evidence that feathers initially served thermoregulation. Isotopic analysis of its protofeathers confirms they provided insulation against temperature changes, a role that came before any signs of flight.

“The protowings triggered stronger escape responses than bare forelimbs.”

Experimental Paleontology Trends

The Caudipteryx study reflects a growing trend in paleontology: using experimental methods to test hypotheses about extinct animals’ behavior. By combining robotics, computer simulations, and neurophysiological experiments, researchers are linking fossil records to functional biology. This approach has also been used to study ichthyosaur locomotion and ancient mammal social behavior. As technology improves, such experiments may offer clearer insights into the evolutionary pressures shaping wings. For instance, the 2025 Serikornis analysis, published in Palaeontology, reinforces the gliding hypothesis. This study used high-resolution CT scans and feather morphology to find no evidence of pre-Jurassic wings, suggesting wings were adapted for non-flight roles before being co-opted for aerial movement.

Evolutionary Innovation and Exaptation

Understanding the origins of wings has broader implications for evolutionary biology. It shows how traits can be repurposed for new functions—a concept called exaptation. The shift from non-aerodynamic to aerodynamic wings in dinosaurs and birds may have been driven by multiple pressures, including predation, thermoregulation, and sexual selection. As Jablonski notes, ‘The same structure that once attracted mates or startled prey could later be refined for flight.’ This duality highlights the complexity of evolutionary innovation and the need for interdisciplinary approaches to unravel it. The 2024 Current Biology review, which rejects the flight-first evolution hypothesis due to the high costs of powered flight, further supports the idea that wings evolved for other functions first. This review argues that the metabolic demands of powered flight would have made it unlikely for wings to have emerged as a primary adaptation.