A scientific team has identified an extraordinarily well-preserved Mesozoic Era bird fossilabout the size of a starling, who lived 80 million years ago in what is today Brazila finding that allows us to better understand the evolution of the skull and brain of these animals.
Its description was published in the Nature magazine and, according to researchers, the entire skull has been preserved almost intact, a rarity for any fossil bird, but especially for one so old. This makes it one of the most significant finds of its kind.
The extraordinary three-dimensional preservation of the skull allowed the researchers, led by the Cambridge Universityin the United Kingdom, and the Los Angeles County Museum of Natural Historydigitally reconstruct the brain of the bird, which they have named “Navaornis hestiae”.
Navaornis lived about 80 million years ago in what is now Brazil, before the mass extinction that wiped out all non-avian dinosaurs.
The researchers claim that their discovery could be a kind of ‘rosetta stone’ for determining the evolutionary origins of the modern avian brain, indicates a statement from Cambridge.
The fossil fills a 70-million-year-old gap in understanding how bird brains evolved: between the 150-million-year-old Archeopteryx and modern-day birds.
Similarities to modern birds include a lack of teeth, large eyes, and a tall, globular skull.
Research suggests that Navaornis had more advanced cognitive abilities than Archeopteryxbut most areas of the brain, such as the cerebellum, were less developed, suggesting that it had not yet developed the complex flight control mechanisms of modern birds.
“The brain structure of Navaornis is almost exactly intermediate between Archeopteryx and modern birds, (…) the missing piece fits perfectly,” details Guillermo Navalón, from Cambridge.
Modern birds have some of the most advanced cognitive abilities in the animal kingdom, rivaled only by mammals, and scientists have been trying for years to understand how and when these unique brains evolved. “We have been waiting for the discovery of a fossil exactly like this one,” agrees Daniel Field, also from Cambridge.
Although at first glance the skull of Navaornis resembles that of a small pigeon, closer inspection revealed that it was a member of a group of primitive birds called enantiornites or ‘opposite birds’.
‘Opposite birds’ diverged from modern birds more than 130 million years ago, but they had complex feathers and were probably competent flyers like modern birds. Cognitive abilities may have given Navaornis an advantage when it came to finding food or shelter.
Although the discovery is a significant advance, researchers say it is only the first step in understanding the evolution of bird intelligence.
Navaornis owes its name to William Nava, director of the Marília Museum of Paleontology, in the Brazilian state of São Paulo, who discovered the fossil in 2016 at a site in the neighboring town of Presidente Prudente.