By Stephen Beech via SWNS
A bird brain from the age of dinosaurs reveals the roots of avian intelligence, according to a new study.
The “one of a kind” fossil discovery could transform our understanding of how the unique brains and intelligence of modern birds evolved, say scientists.
Researchers identified the “remarkably well-preserved” bird, around the size of a starling, as being around 80 million years old.
It lived in what is now Brazil before the mass extinction event that killed all non-avian dinosaurs, according to the study published in the journal Nature.
The complete skull has been preserved almost intact, which scientists say is a rarity for any fossil bird – particularly for one so old.
The three-dimensional preservation of the skull allowed the research team, led by scientists at the University of Cambridge and the Natural History Museum of Los Angeles County, to digitally reconstruct the brain of the bird, which they have named Navaornis hestiae.
They say the discovery could be a kind of “Rosetta Stone” for determining the evolutionary origins of the modern avian brain.
The fossil fills a 70-million-year gap in understanding of how the brains of birds evolved: between the 150-million-year-old Archaeopteryx, the earliest known bird-like dinosaur, and today’s birds.
Navaornis had a larger cerebrum than Archaeopteryx, suggesting it had more advanced cognitive capabilities than the earliest bird-like dinosaurs.
But most areas of its brain, including the cerebellum, were less developed, suggesting that it hadn’t yet evolved the flight control mechanisms of modern birds.
Study co-lead author Dr Guillermo Navalón, of Cambridge’s Department of Earth Sciences, said: “The brain structure of Navaornis is almost exactly intermediate between Archaeopteryx and modern birds – it was one of these moments in which the missing piece fits absolutely perfectly.”
He explained that navaornis is named after William Nava, director of the Museu de Paleontologia de Marília in Brazil’s São Paolo State, who discovered the fossil in 2016 at a site in the neighboring locality of Presidente Prudente.
Tens of millions of years ago, the site was probably a dry area with slow-flowing creeks, which helped to preserve the fossil.
The preservation allowed the research team to use state-of-the-art micro-CT scanning technology to reconstruct the bird’s skull and brain in remarkable detail.
Dr Navalón said: “This fossil is truly so one-of-a-kind that I was awestruck from the moment I first saw it to the moment I finished assembling all the skull bones and the brain, which lets us fully appreciate the anatomy of this early bird.”
Study senior author Professor Daniel Field, from Cambridge’s Department of Earth Sciences, said: “Modern birds have some of the most advanced cognitive capabilities in the animal kingdom, comparable only with mammals.
“But scientists have struggled to understand how and when the unique brains and remarkable intelligence of birds evolved—the field has been awaiting the discovery of a fossil exactly like this one.”
The research team said knowledge of the evolutionary transition between the brains of Archaeopteryx and modern birds was “practically non-existent” before the discovery.
Dr Navalón said: “This represents nearly 70 million years of avian evolution in which all the major lineages of Mesozoic birds originated – including the first representatives of the birds that live today.
“Navaornis sits right in the middle of this 70-million-year gap and informs us about what happened between these two evolutionary points.”
Field added: “This fossil represents a species at the midpoint along the evolutionary journey of bird cognition.
“Its cognitive abilities may have given Navaornis an advantage when it came to finding food or shelter, and it may have been capable of elaborate mating displays or other complex social behavior.”
Study co-lead author Dr Luis Chiappe, from the Natural History Museum of Los Angeles County, said: “This discovery shows that some of the birds flying over the heads of dinosaurs already had a fully modern skull geometry more than 80 million years ago.”
The researchers believe many more finds from the Brazilian site where it was discovered could offer further insights into bird evolution.
Field added: “This might be just one fossil, but it’s a key piece in the puzzle of bird brain evolution.
“With Navaornis, we’ve got a clearer view of the evolutionary changes that occurred between Archaeopteryx and today’s intelligent, behaviourally complex birds like crows and parrots.”
