New research reveals that pterosaurs, the first vertebrates to achieve powered flight, developed the necessary brain structures for aerial locomotion without the dramatic brain enlargement seen in birds. An international team used advanced 3D imaging to reconstruct the brains of over three dozen species, including pterosaurs, their closest relatives, early dinosaurs, crocodiles, and birds. The study suggests that these flying reptiles achieved flight quickly, with a brain structure more akin to non-flying dinosaurs than modern birds.
Rapid Evolution of Flight in Pterosaurs
Pterosaurs appeared roughly 220 million years ago, already capable of powered flight – a capability that evolved separately in avian dinosaurs. This new study challenges the long-held assumption that larger brains were essential for early flight.
The key finding is that pterosaurs evolved flight early in their evolutionary history, and did so with brains that were relatively small compared to their body size. Researchers at Johns Hopkins University School of Medicine found no evidence that enlarged brains were the initial driver of their flight ability.
“Our study shows that pterosaurs evolved flight early on in their existence and that they did so with a smaller brain similar to true non-flying dinosaurs,” said Dr. Matteo Fabbri.
The Role of Vision and Early Adaptations
The team focused on the optic lobe, the brain region responsible for vision, as a potential key to flight. They examined the brains of Ixalerpeton, a Triassic-era lagerpetid – a flightless, tree-dwelling relative of pterosaurs – and found that it already possessed features linked to improved vision, including an enlarged optic lobe.
This suggests that enhanced vision may have been a stepping stone towards flight for pterosaurs. However, the overall brain shapes and sizes between Ixalerpeton and pterosaurs showed very few similarities, implying that pterosaurs acquired flight in a burst, rapidly transforming their brains to meet the demands of aerial locomotion.
Contrast with Bird Evolution
The study contrasts sharply with the evolutionary path of birds. While pterosaurs seemingly “acquired flight from the beginning,” modern birds appear to have developed flight in a more gradual, step-by-step process.
Birds inherited traits like enlarged cerebellums and optic lobes from their prehistoric ancestors, and then adapted them over time for flight. A 2024 study even pointed to the expansion of the cerebellum as a key component in bird flight.
“Essentially, pterosaur brains quickly transformed acquiring all they needed to take flight from the beginning,” Dr. Fabbri explained.
Broader Implications for Understanding Flight
Researchers also analyzed brain cavities in fossils from crocodilians and extinct birds, confirming that pterosaur brains were moderately enlarged but still similar in size to other dinosaurs.
Paleontologist Dr. Rodrigo Temp Müller highlighted that discoveries in southern Brazil continue to refine our understanding of early dinosaur and pterosaur evolution.
This research underscores that there isn’t one single way to evolve flight. Pterosaurs demonstrate that complex adaptations can arise rapidly, even without significant brain enlargement, while birds followed a more gradual, incremental path.
Future studies will focus on the finer details of pterosaur brain structure, aiming to unlock the fundamental biological principles behind flight. The findings appear in the journal Current Biology.
