Before birds took to the sky, reptiles ruled the air for millions of years

Nature · Published 25 October 2026 Swipe more like this →

In short: Birds did not invent vertebrate flight; they inherited a kingdom already dominated by pterosaurs. These prehistoric reptiles mastered powered flight using unique wing structures and specialized tail vanes, evolving from small, flightless ancestors into giants with wingspans exceeding 30 feet.

Pterosaurs were the first vertebrates to achieve powered flight, appearing in the fossil record approximately 220 million years ago. Unlike modern birds, their wings were supported by an enormously elongated fourth finger supporting a vast membrane of living tissue. To sustain this aerial lifestyle, they evolved lightweight bones to reduce mass, powerful muscles for propulsion, and efficient respiration systems to support high metabolisms.

A major mystery regarding pterosaur stability was recently solved using Laser Simulated Fluorescence on the 150-million-year-old fossils of Rhamphorhynchus. Researchers discovered a lattice-like vane at the tip of their tails made of interwoven membranes. This structure functioned like a ship's sail, becoming tense as wind passed through it to prevent fluttering and provide steering, a crucial adaptation for early flight.

The evolutionary path to these giants is now being clarified by the discovery of lagerpetids—small, insectivorous, possibly bipedal reptiles living between 201 and 237 million years ago. While not direct ancestors, lagerpetids shared 33 skeletal features with pterosaurs, including specific anatomy of the inner ear, braincase, and pelvic bones. These shared traits suggest a relatively recent common ancestor, providing a blueprint for how flightless reptiles eventually transitioned into the masters of the sky.

Pterosaurs remained dominant for over 100 million years before perishing alongside the dinosaurs during the Cretaceous-Paleogene mass extinction about 66 million years ago. Their evolution from small long-tailed fliers to ocean soarers and massive aerial predators highlights a distinct evolutionary trajectory from their dinosaur cousins.

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