Uncovering Avian Intelligence: Insights from Dinosaurs’ Feathered Ancestors

Scientists have discovered a remarkably preserved fossilized bird from the Mesozoic Era, about the size of a starling. This near-complete skull is an exceptional discovery for ancient fossils, making it one of the most important of its kind.

The outstanding three-dimensional preservation of this skull enabled the research team, led by the University of Cambridge and the Natural History Museum of Los Angeles County, to digitally recreate the bird’s brain, which they named Navaornis hestiae. This species existed around 80 million years ago in what is now Brazil, before the mass extinction that wiped out non-avian dinosaurs.

The researchers believe that their finding, published in the journal Nature, could serve as a crucial clue for uncovering the evolutionary beginnings of the modern bird brain. This fossil bridges a 70-million-year gap in knowledge regarding bird brain evolution, linking the 150-million-year-old Archaeopteryx, the earliest known bird-like dinosaur, with contemporary birds.

Navaornis had a more developed cerebrum than Archaeopteryx, hinting at advanced cognitive abilities compared to these earlier bird-like dinosaurs. Nonetheless, various brain regions, such as the cerebellum, were less refined, indicating that Navaornis hadn’t yet developed the sophisticated flight control seen in today’s birds.

“The brain structure of Navaornis is nearly perfectly intermediate between that of Archaeopteryx and modern birds — it’s a perfect fit for the evolutionary puzzle,” noted co-lead author Dr. Guillermo Navalón from Cambridge’s Department of Earth Sciences.

Named in honor of William Nava, director of the Museu de Paleontologia de Marília in São Paulo State, Brazil, who unearthed the fossil in 2016 in a neighboring area, Navaornis was preserved exquisitely due to its environment tens of millions of years ago, likely consisting of a dry region with slow-moving streams. This exceptional preservation enabled the use of advanced micro-CT scanning technology to create detailed reconstructions of the bird’s skull and brain.

“This fossil is so exceptional that I was mesmerized from the moment I saw it to when I completed assembling the skull and brain, allowing us to fully understand the anatomy of this early bird,” said Navalón.

“Modern birds exhibit some of the most sophisticated cognitive skills in the animal kingdom, rivaling only those of mammals,” commented Professor Daniel Field from Cambridge’s Department of Earth Sciences, the study’s senior author. “However, scientists have found it challenging to grasp when and how birds developed their exceptional brains and intelligence — this field has been eagerly awaiting a fossil just like this one.”

Before this discovery, there was almost no understanding of the evolutionary shift between the brains of Archaeopteryx and present-day birds. “This represents nearly 70 million years of avian evolution during which all major Mesozoic bird lineages emerged, including the earliest ancestors of modern birds,” added Navalón. “Navaornis occupies a critical position within this 70-million-year span and sheds light on the evolution occurring between these two points.”

Although the skull of Navaornis might initially resemble that of a small pigeon, deeper analysis reveals it belongs to a group of early birds known as enantiornithines, or ‘opposite birds.’

‘Opposite birds’ diverged from modern birds over 130 million years ago and were capable flyers with complex feathers. However, Navaornis raises intriguing questions about how these birds managed flight without all the brain features found in extant birds, especially the larger cerebellum, crucial for spatial awareness in flying birds.

“This fossil represents a species at a crucial stage in bird cognitive evolution,” said Field, who is also the Strickland Curator of Ornithology at Cambridge’s Museum of Zoology. “Its cognitive abilities may have provided Navaornis with an edge in locating food or shelter, and it may have engaged in intricate mating rituals or other sophisticated social interactions.”

“This discovery indicates that some birds soaring above dinosaurs already possessed a modern skull structure over 80 million years ago,” stated co-lead author Dr. Luis Chiappe from the Natural History Museum of Los Angeles County.

While Navaornis is among the best-preserved bird fossils from the Mesozoic Era, researchers anticipate that further discoveries from the Brazilian site may provide additional insights into bird evolution.

“Although this is just one fossil, it plays a vital role in unraveling the mystery of bird brain evolution,” remarked Field. “With Navaornis, we gain a better understanding of the evolutionary transformations that transpired between Archaeopteryx and today’s highly intelligent and socially complex birds like crows and parrots.”

While this discovery marks a significant advancement, the researchers emphasize that it is merely the initial step in comprehending the evolution of avian intelligence. Future studies could explore how Navaornis interacted with its surroundings, contributing to broader inquiries into the progression of bird cognition over the ages.

Navaornis is the latest in a series of Mesozoic bird fossils described by Field’s research team since 2018, joining Ichthyornis, Asteriornis (the ‘Wonderchicken’), and Janavis. Their work on new fossil finds, coupled with advanced visualization and analytical methods, has illuminated fundamental aspects of the origins of birds, the most diverse group of living vertebrates.

This research received partial support from UK Research and Innovation (UKRI). Daniel Field is a Fellow of Christ’s College, Cambridge.