The pterosaur rapidly evolved flight abilities, in contrast to modern bird ancestors, new study suggests
Johns Hopkins Medicine
image:
Reconstruction of a Late Triassic landscape (approximately 215 million years ago). A lagerpetid, a close relative of pterosaurs, is perched on a rock, observing pterosaurs flying overhead.
view moreCredit: Matheus Fernandes
In a study of fossils, a research team led by an evolutionary biologist at Johns Hopkins Medicine suggests that a group of giant reptiles alive up to 220 million years ago may have acquired the ability to fly when the animal first appeared, in contrast to prehistoric ancestors of modern birds that developed flight more gradually and with a bigger brain.
A report on the study, which used advanced imaging tools to study the brain cavities of pterosaur fossils, and was funded in part by the National Science Foundation, was published Nov. 26 in Current Biology.
The findings add to evidence that enlarged brains seen in modern birds and presumably in their prehistoric ancestors were not the driver of pterosaurs’ ability to achieve flight, says Matteo Fabbri, Ph.D., assistant professor of functional anatomy and evolution at the Johns Hopkins University School of Medicine.
“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,” Fabbri says.
Fabbri says the pterosaur was a force to be reckoned with in dinosaur skies, weighing up to 500 pounds and with a wingspan of up to 30 feet in some species. It is known to be the oldest of three groups of flying vertebrates (in addition to birds and bats) that independently evolved self-powered flight.
To learn whether pterosaurs acquired flight differently than birds and bats, the scientists studied the reptile’s evolutionary tree to pinpoint the evolution of pterosaur brain shape and size, looking for clues that may have led to the development of flight. They focused particularly on the area involved in vision, the optic lobe, the growth of which is thought to be associated with flying abilities.
Using CT scans and imaging software that allowed the scientists to extract information about the nervous systems of fossils, the researchers honed in on the pterosaur’s closest relative initially described by a team of researchers in 2016, the flightless, tree-dwelling lagerpetid that originated during the Triassic period 242 to 212 million years ago. In 2020, another group of scientists characterized the lagerpetid’s close relation to the pterosaur.
“The lagerpetid's brain already showed features linked to improved vision, including an enlarged optic lobe, an adaptation that may have later helped their pterosaur relatives take to the skies,” says corresponding author Mario Bronzati, a researcher at University of Tübingen, Germany.
A larger optic lobe was also present in pterosaurs, Fabbri says. However, he says there were otherwise very few similarities in the shape and size of pterosaur brains and that of the flying reptile’s closest relative, the lagerpetid.
“The few similarities suggest that flying pterosaurs, which appeared very soon after the lagerpetid, likely acquired flight in a burst at their origin,” Fabbri says. “Essentially, pterosaur brains quickly transformed acquiring all they needed to take flight from the beginning.”
By contrast, modern birds are believed to have acquired flight in a step-by-step, more gradual process, inheriting certain features, such as an enlarged cerebrum, cerebellum and optic lobes from their prehistoric relatives, and later adapting them to enable flight, says Fabbri. This theory is supported by 2024 findings from the lab of Amy Balanoff, Ph.D., assistant professor of functional anatomy and evolution at Johns Hopkins Medicine, that point to the expansion of the brain’s cerebellum as a key to bird flight. The cerebellum, located at the back of the brain, regulates and controls muscle movement among other activities.
“Any information that can fill in the gaps of what we don’t know about dinosaur and bird brains is important in understanding flight and neurosensory evolution within pterosaur and bird lineages,” Balanoff says.
In further studies, the scientists analyzed brain cavities of fossils from crococdylians (crocodile ancestors) and early, extinct birds, and compared these with pterosaur brain cavities.
They determined that the pterosaur's brain had moderately enlarged hemispheres, similar in size to other dinosaurs—including two-legged bird-like troodontids living during the Late Jurassic to the Late Cretaceous periods 163 to 66 million years ago, and the oldest-known bird, Archaeopteryx lithographica from 150.8 million to 125.45 million years ago—compared with the brain cavities of modern birds.
In the future, Fabbri says that better understanding how the structure of the pterosaur brain, in addition to the size and shape, enabled flight will be the most important step to better infer the basic biological laws of flight.
Funding support for this research was provided by the Alexander von Humboldt Foundation, Brazilian Federal Government, The Paleontological Society, Agencia Nacional de Promoción Científica y Técnica, Conselho Nacional de Desenvolvimento Científico e Tecnológico, the European Union NextGeneration EU/PRTR, the National Science Foundation ( NSF DEB 1754596, NSF IOB-0517257, IOS-1050154, IOS-1456503), and the Swedish Research Council
In addition to Fabbri and Bronzati, other scientists who contributed to this research are Akinobu Watanabe from New York Institute of Technology, Roger Benson from the American Museum of Natural History, Rodrigo Müller from Federal University of Santa Maria, Brazil, Lawrence Witmer from the University of Ohio, Martín Ezcurra and M. Belén von Baczko from Bernardino Rivadavia Museum of Natural Science, Felipe Montefeltro from São Paulo State University; Bhart-Anjan Bhullar from Yale University; Julia Desojo from Universidad Nacional de La Plata, Argentina; Fabien Knoll from Museo Nacional de Ciencias Naturales, Spain; Max Langer from Universidade de São Paulo, Brazil; Stephan Lautenschlager from University of Birmingham; Michelle Stocker and Sterling Nesbitt from from Virginia Tech; Alan Turner from Stony Brook University; and Ingmar Werneburg from Eberhard Karls University of Tübingen.
Journal
Current Biology
Evolving a flight-ready brain – New study shows brain evolution in pterosaurs and birds took different paths
Discovery of a new 233-million-year-old nonflying relative of pterosaurs provides breakthrough
Ohio University
Artistic reconstruction of a pterosaur (top) and a lagerpetid (bottom) from the Late Triassic period (around 215 million years ago). Credit Matheus Fernandes
Tübingen, Germany (Nov. 26, 2025) - Flight is a rare skill in the animal world. Among vertebrates, it evolved only three times: in bats, birds, and the long-extinct pterosaurs. Pterosaurs were the pioneers, taking to the skies more than 220 million years ago, long before early bird relatives such as Archaeopteryx appeared, around 150 million years ago. While scientists have a detailed fossil record that sheds light on how birds’ brains evolved for flight, the same story for pterosaurs has been far less clear. Until now.
In a new study published in Current Biology, an international team now reveals how pterosaurs evolved the neurological structures required for powered flight.
“The breakthrough was the discovery of an ancient pterosaur relative, a small lagerpetid archosaur named Ixalerpeton from 233-million-year-old Triassic rocks in Brazil,” said Mario Bronzati, an Alexander von Humboldt fellow at the University of Tübingen in Germany and lead author of the study.
“We’ve had abundant information about early birds and knew they inherited their basic brain layout from their theropod dinosaur ancestors,” added coauthor Lawrence Witmer, professor of anatomy at the Ohio University Heritage College of Osteopathic Medicine. “But pterosaur brains seemed to appear out of nowhere. Now, with our first glimpse of an early pterosaur relative, we see that pterosaurs essentially built their own ‘flight computers’ from scratch.”
To piece together this evolutionary story, the researchers used high-resolution 3D imaging techniques, including microCT scanning, to reconstruct brain shapes from more than three dozen species. These included pterosaurs, their close relatives like Ixalerpeton, early dinosaurs and bird precursors, modern crocodiles and birds, and a wide range of Triassic archosaurs, the larger group that includes all these animals.
“Then, using statistical analysis of the size and 3D shape of their cranial endocasts, we were able to map the stepwise changes in brain anatomy that accompanied the evolution of flight,” said coauthor Akinobu Watanabe, associate professor of anatomy at the New York Institute of Technology College of Osteopathic Medicine.
Flight is a physiologically demanding form of locomotion and has long been assumed to require major neurological adaptations including enlargement of the brain to coordinate the complicated sensory and motor information required for powered flight. Previous studies of pterosaur brain structure had shown that they indeed shared some neurological similarities with bird precursors like Archaeopteryx, such as some enlargement of brain regions like the cerebrum and cerebellum involved with sensorimotor integration, as well as enlargement of visual centers like the optic lobes.
Ixalerpeton, the lagerpetid close relative of pterosaurs showed some but not all neurological traits of pterosaurs. For example, as Bronzati notes, “lagerpetids were probably tree-dwellers, and their brains already show features linked to improved vision, such as an enlarged optic lobe, an adaptation that may have later helped their pterosaur relatives take to the skies, but they still lacked key neurological traits of pterosaurs.”
Lagerpetids like Ixalerpeton had brains intermediate in shape between more primitive archosaurs and pterosaurs but retain greater similarity to early dinosaurs. Other than the enlarged optic lobe that occupies a position in the brain similar to that in pterosaurs and birds and their close theropod relatives, there is little in Ixalerpeton that indicates what was to come in pterosaurs. A unique feature of the brain of pterosaurs is a greatly enlarged flocculus, a structure of the cerebellum likely involved in processing sensory information from their membranous wings to keep their eyes fixed on a target while in flight. The flocculus in Ixalerpeton wasn’t expanded like pterosaurs, instead resembling the modest flocculus of other archosaurs, including early birds and their close nonavian theropod relatives.
Likewise, the new analyses show that pterosaurs retained modest brain sizes.
“While there are some similarities between pterosaurs and birds, their brains were actually quite different, especially in size,” said coauthor Matteo Fabbri, assistant professor of Functional Anatomy and Evolution at the Johns Hopkins University School of Medicine. “Pterosaurs had much smaller brains than birds, which shows that you may not need a big brain to fly.”
Surprisingly, the overall brain shape of pterosaurs most closely resembled that of small, bird-like dinosaurs such as troodontids and dromaeosaurids, animals that had little or no powered flight ability. Yet pterosaurs and birds still represent two entirely independent experiments in the evolution of flight. Birds inherited a brain already adapted from their non-flying dinosaur ancestors, while pterosaurs evolved their flight-ready brains at the same time they developed their wings.
Birds’ notably large brains, the authors note, likely came later and were tied more to increasing intelligence and complex behaviors rather than the act of flying itself. A key takeaway from the study is that, according to Witmer, “it apparently doesn’t take a large brain to get into the air, and the later brain expansion in both birds and pterosaurs was likely more about enhancing cognition than about flying itself.”
Another important takeaway is that paleontological fieldwork remains an engine for new breakthroughs.
“Discoveries from southern Brazil have given us remarkable new insights into the origins of major animal groups like dinosaurs and pterosaurs,” coauthor Rodrigo Temp Müller, a paleontologist at Universidade Federal de Santa Maria, Brazil, noted. “With every new fossil and study, we’re getting a clearer picture of what the early relatives of these groups were like, something that would have been almost unimaginable just a few years ago.”
The full list of coauthors includes: Mario Bronzati, Akinobu Watanabe, Roger B. J. Benson, Rodrigo T. Müller, Lawrence M. Witmer, Martín D. Ezcurra, Felipe C. Montefeltro, M. Belén von Baczko, Bhart-Anjan S. Bhullar, Julia B. Desojo, Fabien Knoll, Max C. Langer, Stephan Lautenschlager, Michelle R. Stocker, Alan H. Turner, Ingmar Werneburg, Sterling J. Nesbitt, and Matteo Fabbri.
The research was funded by the Alexander von Humboldt Foundation, Germany; Financiadora de Estudos e Projetos - Brazilian Federal Government; a Sepkoski Grant of the Paleontological Society; Agencia Nacional de Promoción Científica; Conselho Nacional de Desenvolvimento Científico e Tecnológico; INCT Paleovert’ European Union NextGeneration; the U.S. National Science Foundation; and the Swedish Research Council.
Journal
Current Biology
Method of Research
Imaging analysis
Subject of Research
Animals
Article Title
Neuroanatomical convergence between pterosaurs and non-avian paravians in the evolution of flight
Article Publication Date
26-Nov-2025
Artistic reconstruction of a pterosaur (top) and a lagerpetid (bottom) from the Late Triassic period (around 215 million years ago). The images on the right show 3D reconstructions of their brains obtained through computed tomography (CT) scanning.
Credit
Rodrigo Müller, Mario Bronzati, Matheus Fernandes
