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Photo, caption follows:

Entombed in fossilized skulls of Rhamphorhynchus muensteri (upper, background) and Anhanguera santanae (lower, foreground) are the remains of semi-circular canals (shown in green), the inner-ear structures that assist in equilibrium maintenance by providing leveling information to the brain.
Credit: Kyle McQuilkin, Ryan Ridgely, Ohio University

What Is Our Relationship to Our Surroundings?
With a 13-foot wingspan, a flying dinosaur soars above a lake, scanning for dinner as its shadow glides across the water's surface below. Spotting a fish, the reptile, called a pterosaur, dives through the air until, with a splash, the fish is in the pterosaur's beak.

While such a scene hasn't occurred in more than 100 million years, a study funded by NSF's Biological Sciences Directorate gives a clearer picture of what went on inside the pterosaur's head while it was fishing. When scientists using fossil skulls examined the neuroanatomy responsible for flight control and prey spotting, they found structures that were specialized and enlarged, a discovery that could revise views of how vision, flight and the brain itself evolved.

This research, led by Lawrence Witmer of Ohio University, took a high-tech look through two skulls of separate species of pterosaurs. Using computerized images derived from x-rays, they peered into the vestibular apparatus, the passageways and chambers responsible for maintaining equilibrium. They also went "virtually" into the brain cavity to analyze the regions responsible for coordinating wing movements, for scanning the environment and for stabilizing vision, a necessity for airborne predators of the past--and of today.

To examine the skulls' chambers, which were encased in mineralized fossils, the scientists used non-invasive, computerized axial tomography, more commonly known as CAT, or CT, scans.

The researchers found a greatly enlarged neurological structure critical to flight. Called the flocculus, this lobe of the cerebellum has important connections with the vestibular apparatus, the eye muscles and neck muscles, which all work together to stabilize and sharpen an image of a prey animal upon a predator’s retina.

The discovery has led to a better understanding of how birds and other animals, including humans, perceive the world around them.

What connects fish and maple trees? [Next]