Artistic representation of Archaeopteryx, N. hestiae, and a modern-day bird (right): brain and inner ear comparedJúlia d’Oliveira
A skeleton of a toothless bird, with large eyes set in a tall, round skull, could help explain how the avian brain evolved. The bones, found in the interior of São Paulo, are very well preserved, which is unusual for birds because their fragile bones rarely leave fossil records. The new species, named Navaornis hestiae, lived between 83 million and 72 million years ago. Paleontologists took advantage of the fossil’s good condition to perform a digital tomography scan, from which they created a 3D reconstruction of the animal’s head and an interpretive drawing. They then compared the degree of expansion of brain structures of N. hestiae with several dinosaur species and the bird genus Charadrius, which still exists today. They found that the newly discovered species had intermediate characteristics between primitive birds and their descendants. The lack of teeth, the size and height of the eyes and skull, the shape of the bony labyrinth, and the degree of brain flexion are very similar to those of modern birds. On the other hand, the large maxilla, palate, small cerebellum, and not very expansive telencephalon are more closely related to ancestral birds, such as Archaeopteryx. “This is information that we have been seeking for a long time. The discovery allows us to understand how and when the evolutionary processes, and even the neuroanatomy, that led to the origin of modern birds occurred,” says paleontologist Ismar Carvalho of the Federal University of Rio de Janeiro (Nature, November 13).
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