A 300 million-year-old fossilized fish brain was discovered during
a routine computed tomography (CT) scan, according to a study published today in the
Proceedings of the National Academy of Sciences. Until now, scientists assumed that brains rarely—if ever—turned into
fossils. Other soft tissue fossils, such as muscles and kidneys, have been found that date back longer than 350 million years ago, but because the brain is delicate and consists mostly of water, it's much less likely to be preserved in fossil form, says study co-author
John Maisey, a curator in the paleontology division of the American Museum of Natural History in New York. But "It's more than just a curiosity," he says. "Modern technology has revealed a fossil that we really didn't know about before." High-powered scans using x-ray synchrotron microtomography (which, like a CT, uses x-rays to image cross-sections of an object) allowed scientists to peer into the rock-solid skull to see the 0.06-by-0.28-inch (1.5 by 7 mm) brain.
The fossil was from an iniopterygian, an ancient extinct fish that is a relative of sharks, rays and ratfish. What surprised researchers even further is that it showed
a brain similar to that of modern-day shark.
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off site, courtesy Scientific American.