FLIGHT was built into the brain as well as the body of Archaeopteryx. The oldest known bird shares many skeletal features with its dinosaur ancestors, such as teeth and a long bony tail. Yet a CAT scan reveals that Archaeopteryx had the large brain and optic lobes of modern birds, not the brain of a dinosaur, says Angela Milner of London鈥檚 Natural History Museum.
It is relatively easy to study how a fossil skeleton may have been adapted for flight. However, navigating in a three-dimensional environment also requires a specialised brain. Modern birds have an enlarged brain, optic lobes and keen ears with spatial sensing organs, but little had been known about the brain of Archaeopteryx.
So Milner鈥檚 team investigated the London specimen of Archaeopteryx, the only one suitable for scanning. A three-dimensional image created from the scan shows the bird had a relatively large cerebellum, 鈥渢he area where all the coordination and control goes on鈥�, Milner says. The optic lobes, which had also expanded to provide more visual input, were pushed to the side. The inner ear also resembled that of modern birds, suggesting that Archaeopteryx had similar hearing and balance-sensing capabilities.
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According to Milner, the new study builds a good case for powered flight being dependent on both an aerodynamic wing and a strong central nervous system (Nature, vol 430, p 666). 鈥淚t is critical data,鈥� says Larry Witmer of Ohio University in Athens, who last year reported that pterosaurs also had large brains and optic lobes. 鈥淣eural control has been a missing part of the story of the origin of flight.鈥�
By showing that getting off the ground requires spatial sensing and control as well as wings, the study opens up new ways to examine the origin of flight. 鈥淭he big question now is what the brain and ear are like in the most bird-like dinosaurs,鈥� Witmer says.
