Humid air gave pterosaurs the boost they needed to take flight

The skies were empty for most of Earth’s history, but then light‑boned reptiles mastered powered flight roughly 220 million years ago.

A new analysis of fossil maps and computer climate models shows that warm, damp air, not desert heat, gave those first pterosaurs the environmental boost they needed.

Davide Foffa of the University of Birmingham led the work with Emma Dunne at Friedrich‑Alexander‑Universität Erlangen‑Nürnberg and Alessandro Chiarenza at University College London.

Pterosaurs lived in humid regions

Foffa’s team plotted every Triassic pterosaur and lagerpetid fossil they could verify, covering what was then the single supercontinent Pangea.

The map revealed a pattern: early flyers cluster in low‑latitude sites that ancient climate simulations mark as humid, while their land‑bound cousins spread across drier belts.

Lagerpetids, rat‑ to dog‑sized sprinters, never left the ground yet roamed from today’s Brazil to the American Southwest. Ezcurra and colleagues confirmed in 2020 that these agile reptiles form the sister branch to pterosaurs.

Pterosaur flight needed humid forests

The question of why pterosaurs took flight when they did has puzzled researchers for decades. Their closest relatives, lagerpetids, had the anatomical tools for agility and climbing, but lacked the skeletal adaptations needed for powered flight.

Foffa’s team suggests it wasn’t just biology holding them back – it was the environment. Without expansive forest canopies and consistently humid ecosystems, early pterosaur ancestors may have lacked both the resources and the ecological pressure to evolve wings sooner.

Rainfall surge led to pterosaur flight

As carbon‑rich volcanism drove the Carnian Pluvial Episode about 234 million years ago, average rainfall spiked for roughly two million years. Forests thickened, insect populations jumped, and treetop launchpads multiplied exactly when the first pterosaur bones appear.

To test cause and effect, the authors fed Triassic geography into the HadCM3L general circulation model, a tool normally used for Cretaceous and future‑climate work.

The simulation reproduced humid bands along the equator that matched every known Norian pterosaur site within a margin of about 60 miles.

Fossils and climate maps tell the story

To connect ancient reptile evolution with prehistoric climate, the researchers needed more than just bones. They used global climate models that simulate temperature, precipitation, and seasonal variation from over 200 million years ago, then overlaid fossil data on those maps.

This approach revealed strong patterns. Pterosaur fossils linked to flight consistently appeared in regions the model predicted to be wet and forested.

On the other hand, lagerpetids showed up in a broader range of habitats, including dry, seasonal areas. These overlapping maps helped confirm the environmental preferences of each group.

Humid air and the rise of flying reptiles

“Their wings catapulted them into every corner of the planet,” noted Chiarenza. Later Triassic decades saw wetter air creep poleward, and the fossil record follows: specimens pop up in what is now Greenland and Argentina, hundreds of miles from the original belt.

Marine records show that the same wet pulse coincided with a 33 percent loss of ocean genera and rapid dinosaur diversification, hinting at a broader reshuffling.

Dunne noted that climate change is a leading cause of biodiversity change, both in the present day and the geological past – a reminder that weather can redraw evolutionary maps.

Pterosaur flight aided survival for some

Lagerpetids tolerated scorchingly dry interiors yet vanished at the end‑Triassic extinction, while their winged relatives sailed through the crisis. Flight likely offered escape from predators and fire, plus access to scattered resources after forests burned.

The disappearance of lagerpetids at the end of the Triassic remains a mystery, especially since they had a broader climate tolerance and geographic range than early pterosaurs.

Some scientists suggest they may have lacked the specialized adaptations – like flight – that helped other groups escape or adapt to rapid ecosystem changes.

Others think competition may have played a role. As pterosaurs and early dinosaurs spread into new environments, they may have outcompeted lagerpetids for food or territory, leaving the once-thriving reptiles with fewer niches to occupy.

Clues for future fossil hunts

“Model outputs flag humid Triassic pockets in Morocco, India, and the American Midwest where no pterosaur bones have been logged. Field crews may strike pay dirt there, especially in fine‑grained lake shales that entomb fragile skeletons whole,” explained Foffa.

The research links a short‑lived climate swing to a permanent ecological shake‑up in which pterosaur flight emerged, demonstrating how quickly new winners appear when habitats shift.

With modern CO₂ levels rising on a similar scale, today’s ecosystems could see equally swift turnovers, though not necessarily as majestic as a Pterosauromorpha liftoff.

The study is published in the journal Nature Ecology & Evolution.

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