Before birds ruled the skies, some dinosaurs experimented with bat-like membranous wings.

Nature · Published 3 October 2026 Swipe more like this →

In short: While we often associate dinosaurs with feathers, a strange group called Scansoriopterygidae took a different path. These small, tree-dwelling theropods evolved unique membranous wings supported by elongated fingers and a mysterious wrist structure. This short-lived evolutionary experiment reveals how diverse the early attempts at flight truly were among dinosaurs.

The Scansoriopterygidae represent a fascinating, if brief, chapter in the evolution of flight. Unlike the feathered wings that eventually defined the avian lineage, these dinosaurs utilized a membranous flight apparatus. This structure, supported by an elongated third finger and a specialized styliform bone extending from the wrist, bears a striking, if superficial, resemblance to the wings of modern bats and ancient pterosaurs. This discovery, bolstered by specimens like Yi qi and the more recently identified Ambopteryx longibrachium, suggests that such wing architecture was a widespread feature within this specific clade.

These findings, primarily emerging from fossil sites in China, have forced paleontologists to rethink the path to volant behavior. Scansoriopterygids appear to have been small, arboreal creatures that occupied a distinct evolutionary niche. Their existence implies that as dinosaurs approached the origin of flight, they were not following a single, linear trajectory. Instead, they were experimenting with a variety of wing configurations. The membranous wings of the Scansoriopterygidae were likely a specialized adaptation that eventually lost out to the feathered wings favored by the Paraves lineage, which includes modern birds.

The classification of these animals has been a subject of significant scientific debate. Early interpretations of specimens like Scansoriopteryx heilmanni were complicated by the fact that many fossils were juveniles, which may not display the full suite of adult characteristics. Over time, researchers have debated whether these creatures were basal members of the Avialae or occupied a more ambiguous position within the Paraves. Regardless of their exact placement, the Scansoriopterygidae stand as a testament to the biological creativity of the Jurassic period, illustrating a moment when the line between climbing and flying was blurred by a unique, membrane-based solution.

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