Flying poses complex challenges for coordination and orientation. But how did the brains of flying animals adapt to this? Analyzes of fossil and modern skulls of pterosaurs, birds and various land animals show that the thinking organ of pterosaurs had little in common with that of today’s birds. Both groups of animals evolved independently from non-flying ancestors. The pterosaurs apparently only had an astonishingly small brain to take to the skies – which also developed particularly quickly.
Vertebrates independently developed the ability to fly three times during evolution. The first aerial pioneers were the pterosaurs more than 220 million years ago. The first relative of birds, Archeopteryx, evolved from flightless dinosaurs around 150 million years ago. About 100 million years later, mammals also gave rise to flying specimens, the bats.
Ancestors of pterosaurs in sight
“Flying is a complex mode of locomotion that requires physiological adaptations and a dramatic remodeling of the body structure, including changes in body proportions, specialized skin and the acquisition of novel neurosensory abilities,” explains a team led by Mario Bronzati from the University of Tübingen. Although it has long been known that pterosaurs and birds developed their ability to fly independently, scientists previously assumed that their brains showed similar adaptations to locomotion in the air.
But while the brain development of birds is already well documented, there has been a lack of meaningful research into the brains of pterosaurs. Well-preserved skull fossils of early pterosaurs and their ancestors are rare. “It is only in the last few years that we have had evidence of close relatives of the pterosaurs, the so-called lagerpetids, small, two-legged and probably tree-dwelling animals,” reports Bronzati. Fossils of these lagerpetids have already helped to better understand the adaptations in the body structure of pterosaurs. “We were interested in the changes in their brain anatomy that are associated with the development of flight,” says Bronzati.
Brain development like flying
Together with his team, the researcher analyzed the skulls of various flying and non-flying animals, including pterosaurs, dinosaurs, birds, crocodiles, and a small lagerpetid called Ixalerpeton, which was found in 233 million-year-old rocks from the Triassic period in Brazil. “By statistically analyzing the size and 3D shape of their skulls, we were then able to map the gradual changes in brain anatomy that accompanied the evolution of flight,” explains co-author Akinobu Watanabe from the New York Institute of Technology.
It was shown that the brains of the pterosaurs had developed significantly over a short period of time compared to that of their ancestors, the lagerpetids. “Lagerpetid brains already exhibit features associated with enhanced vision, such as an enlarged optic lobe, an adaptation that may have later helped their pterosaur relatives take to the skies,” Bronzati reports. “But they still lacked important neurological features of pterosaurs.” In pterosaurs, for example, a structure in the cerebellum called the flocculus is greatly enlarged. This region likely helped pterosaurs process sensory information from their membranous wings.
Ascent into the skies despite “sparrow brains”
“Now that we can get our first look at an early relative of the pterosaurs, we see that the pterosaurs essentially developed their own ‘flight computers’ from scratch,” says co-author Lawrence Witmer of Ohio University. While birds inherited many of the brain structures important for flight from their flightless dinosaur ancestors, pterosaurs apparently developed their neurological adaptations to flight anew and at the same time as their wings.
However, compared to birds, the brains of early pterosaurs are tiny. This finding contradicts the assumption that the complex motor and sensory challenges of flight require large brains. “Apparently you don’t need a big brain to move in the air,” says Witmer. “Later brain enlargements, in both birds and pterosaurs, probably served to improve cognitive abilities rather than flight itself.”
Source: Mario Bronzati (Eberhard Karls University of Tübingen) et al., Current Biology, doi: 10.1016/j.cub.2025.10.086