Researchers have identified a remarkably well-preserved fossil bird, roughly the size of a starling, from the Mesozoic Era. The complete skull has been preserved almost intact: a rarity for any fossil bird, but particularly for one so ancient, making this one of the most significant finds of its kind.
The extraordinary three-dimensional preservation of the skull allowed the researchers, led by 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. Navaornis lived approximately 80 million years ago in what is now Brazil, before the mass extinction event that killed all non-avian dinosaurs.
The researchers say their discovery, reported in the journal Nature, could be a sort of ‘Rosetta Stone’ for determining the evolutionary origins of the modern avian brain. The fossil fills a 70-million-year gap in our understanding of how the brains of birds evolved: between the 150-million-year-old Archaeopteryx, the earliest known bird-like dinosaur, and birds living today.
Navaornis had a larger cerebrum than Archaeopteryx, suggesting it had more advanced cognitive capabilities than the earliest bird-like dinosaurs. However, most areas of its brain, like the cerebellum, were less developed, suggesting that it hadn’t yet evolved the complex flight control mechanisms of modern birds.