Baptized Navaorni’s hestia and discovered in Brazil, a fossil of around 80 million years old sheds light on the evolution of birds in the animal kingdom, according to a study published Wednesday in Nature.
The centerpiece of the discovery is a small skull less than three centimeters long, including the beak, remarkably preserved. It was discovered in 2016 in a small quarry in the state of São Paulo in Brazil, whose fossils are concentrated in a layer less than 50 cm thick. The exceptional preservation of the small skull made it possible to reconstruct its geometry, which turns out to be similar to that of current birds, including the genus Corvus to which the raven belongs.
A cutting-edge scanning technique then allowed a reconstruction of the fossil’s brain, making it, according to its discoverers, a “Rosetta stone” to better understand the evolution of the bird brain.
Flying skills?
That of Archeopteryx “was much more similar to that of dinosaurs” which did not fly, explains to AFP Professor Daniel Field, in the department of earth sciences at the University of Cambridge, who supervised the study. “Relatively small in relation to its body”, unlike that of modern birds, it was also poorly developed in key regions for cognition and flight, specifies this paleontologist.
“The structure of the brain of Navaornis is almost exactly intermediate between that of Archeopteryx and that of modern birds,” said Dr. Guillermo Navalón, co-author of the study, quoted in a Cambridge press release.
Relative to the size of its body, the brain of the fossil was “much larger” than that of Archeopteryx, continues Professor Field, and “very similar to that of birds living today”. In contrast, its cerebellum, which plays an essential role in controlling flight in modern birds, was apparently less developed.
However, the anatomy of Navaornis and the characteristics of the plumage and soft tissues of related birds suggest a real skill in flight, which perhaps explains the presence in its inner ear of a “gigantic” vestibular apparatus, linked to balance and “much larger than that of modern birds,” Dr. Navalón told AFP. “It seems very plausible” that this characteristic acted as a compensatory mechanism “allowing Navaornis to orient itself in the air,” adds Professor Field.
