A tiny Scottish fossil finally reveals the mysterious origins of the first flying reptiles

Nature · Published 3 October 2026 Swipe more like this →

In short: For over a century, the identity of Scleromochlus was a paleontological puzzle. Was it a dinosaur, a crocodile ancestor, or something else? New microcomputed tomographic scans of this tiny, 230-million-year-old reptile have finally settled the debate, revealing it as a primitive cousin to the pterosaurs and a key to their evolution.

Discovered in the Lossiemouth Sandstone of Scotland, Scleromochlus taylori has long frustrated scientists. Because the fossils were preserved only as natural moulds—impressions in rock rather than actual bone—researchers historically relied on physical casts. These casts often missed minute anatomical details, leading to over a century of conflicting theories that placed the animal everywhere from the dinosaur lineage to the crocodile family tree.

The breakthrough came when researchers used microcomputed tomographic (μCT) scanning to virtually fill in these natural moulds. By examining the seven known specimens in unprecedented detail, the team was able to reconstruct a complete skeleton. This 2022 analysis confirmed that Scleromochlus is a member of the Pterosauromorpha, specifically identifying it as the most primitive member of the lagerpetid group found to date. This discovery is significant because it marks the first time lagerpetids have been identified in Europe, expanding their known range beyond the Americas and Madagascar.

While Scleromochlus was not a direct ancestor of pterosaurs, its anatomy provides a vital window into what those ancestors might have looked like. Pterosaurs appear in the fossil record 220 million years ago already highly specialized for flight, leaving an 18-million-year gap in their evolutionary history. Scleromochlus, which lived 230 million years ago, lacks flight adaptations, suggesting that the distinct pterosaur body plan evolved rapidly during that intervening period. This research highlights how modern scanning technology can breathe new life into museum collections, allowing scientists to resolve long-standing mysteries by uncovering data hidden within previously overlooked fossil blocks.

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