The recently discovered Mesozoic bird fossil Navaornis hestiae provides important information about the evolutionary development of the bird brain, connecting ancient species such as Archeopteryx to modern birds.

A remarkable fossil discovery could change our understanding of how the unique brains and intelligence of birds evolved, a long-standing mystery of vertebrate evolution.

Scientists have discovered an extraordinarily well-preserved fossil bird from the Mesozoic period, comparable in size to a starling. The entire skull was preserved almost intact; This is a rare occurrence for any bird fossil, especially one this old.

The extraordinary three-dimensional preservation of the skull allowed scientists led by the University of Cambridge and the Los Angeles County Museum of Natural History to digitally recreate the brain of the bird, which they named Navaornis hestiae. Navornis lived in what is now Brazil about 80 million years ago, before the mass extinction that wiped out all non-avian dinosaurs.

Scientists say their discovery, published in the journal Nature, may be the “Rosetta Stone” that will help determine the evolutionary origins of the modern bird brain. The fossil fills a 70-million-year gap in our understanding of how bird brains evolved: between the 150-million-year-old Archeopteryx, the oldest known bird-like dinosaur, and modern birds.

Cognitive knowledge of the anatomy of ancient birds

Navornis’s brain was larger than that of Archeopteryx, indicating that it had more advanced cognitive abilities than those of the first bird-like dinosaurs. However, many areas of the brain, such as the cerebellum, are less developed, indicating that modern birds have not yet developed complex flight control mechanisms.

Dr., one of the authors of the study from Cambridge School of Earth Sciences. “The brain structure of Navornis is almost exactly intermediate between Archeopteryx and modern birds; it was one of those moments when the missing piece fit perfectly,” said Guillermo Navalon.

Historical and cultural importance of fossils

Navaornis is named after William Nava, director of the Marilia Museum of Paleontology in the Brazilian state of São Paulo, who discovered the fossil in 2016 in the nearby town of Presidente Prudente. Tens of millions of years ago, this region was probably a dry area with slow-flowing streams, allowing for excellent fossil preservation. This preservation allowed the researchers to reconstruct the bird’s skull and brain in minute detail using advanced micro-CT scanning technology.

“This fossil is truly so unique that I was amazed from the moment I first saw it to the moment I finished collecting all the skull bones and brain, giving us a complete understanding of the anatomy of this early bird,” Navalon said.

Unraveling the evolution of the bird brain

“Modern birds have some of the most complex cognitive abilities in the animal kingdom, comparable only to mammals,” says the study’s senior author, Professor Daniel Field from Cambridge’s Department of Earth Sciences. “But scientists are trying to understand how and when birds’ unique brains and extraordinary intelligence evolved. Field has been waiting for fossils like these to be found.”

Before this discovery, there was almost no information about the evolutionary transition between the brain of Archeopteryx and the brain of modern birds. “This is approximately 70 million years of bird evolution, during which all major lineages of Mesozoic birds emerged, including the first representatives of birds alive today,” Navalon said. “Navornis lies right in the middle of the 70-million-year gap and gives us information about what happened between these two points of evolution.”

Mysterious ancestors: “Opposite birds

Although at first glance the skull of Navornis resembles that of a small pigeon, a closer look reveals that it is not a modern bird but a member of a group of early birds called enantiornithines, or “opposable birds.”

The “opposite birds” diverged from modern birds more than 130 million years ago, but they had complex feathers and were probably able to fly like modern birds. However, the anatomy of Navornis’ brain raises a new question: How were opposable birds able to control their flight without all the brain functions seen in modern birds, including the enlarged cerebellum, the spatial control center of living birds?

Evolutionary significance of Navornis

“This fossil represents a species midway along the evolutionary path of bird cognitive development,” says Field, who is also curator of the Strickland Department of Ornithology at the Cambridge Museum of Zoology. “Cognitive abilities may have given navornies an advantage in finding food or shelter and may have been capable of performing elaborate mating displays or other complex social behaviors.”

Study co-author Dr. of the Natural History Museum of Los Angeles County. “This discovery shows that some birds flying over dinosaur heads already had fully modern skull geometry more than 80 million years ago,” said Luis Chiape.

An important fossil in bird research

Although Navornis is one of the best-preserved bird fossils of the Mesozoic era, researchers believe that many other findings from the Brazilian region where it was found could reveal more about the evolution of birds.

“This may be just a fossil, but it’s an important piece of the puzzle of bird brain evolution,” says Field. “Thanks to Navornis, we have a clearer picture of the evolutionary changes that occurred between Archeopteryx and modern, intelligent, complex birds such as crows and parrots.”

The future of bird evolution research

Although the discovery is a major breakthrough, researchers say it is only the first step in understanding the evolution of bird intelligence. Future research could reveal how Navaornis interacted with its environment and help answer broader questions about the evolution of birds’ cognitive ability over time.