‘You don’t need a big brain to fly’ and other lessons from the first flying reptiles

Flight evolved only three times among vertebrates: in bats, birds, and the extinct flying reptile called pterosaurs.

Of these, pterosaurs were the first to master flight, more than 215 million years ago — long before the appearance of the earliest birds.

For decades, scientists puzzled over how pterosaurs evolved the ability to fly as well as the anatomical changes that made flight possible.

But understanding how flight arose was hampered by a lack of well-preserved pterosaur fossils. To work around this gap, paleontologists have been investigating a close relative of pterosaurs — a flightless two-legged animal group called lagerpetids that lived alongside the earliest dinosaurs in several regions of the world.

Virginia Tech geoscientists were part of an international research team that used CT scanners to digitize fossilized and modern skulls representing a wide array of early land reptiles — including pterosaurs, lagerpetids, and dinosaurs as well as today’s crocodiles and birds.

“Technology like CT scanning gives us ways to ask and address questions that just weren’t possible for so long,” said Virginia Tech geobiologist Michelle Stocker, who co-authored the study published recently in Current Biology with fellow geobiologist Sterling Nesbitt.

By analyzing the high-resolution 3D reconstructions of the brain cavities inside the skulls, the team was able to map the stages of changes in brain shape and size before and after the evolution of flight.

For instance, the brains of lagerpetids displayed features linked to improved vision, such as an enlarged optic lobe, which allowed them to navigate their environments and prey on small organisms. This adaptation may have helped their pterosaur relatives take to the skies more than 200 million years ago.

However, the study also shows that pterosaurs never reached the degree of brain enlargement observed in modern birds, whose sophisticated brain structures were inherited from their dinosaur ancestors.

“Interestingly, we found that pterosaurs had relatively small brains, comparable in size to those of non-flying dinosaurs and much smaller than that of birds,” Nesbitt said.

In other words, you don’t need a big brain to fly.

Original study: DOI:10.1016/j.cub.2025.10.086