World’s Oldest Fossilized Brain Discovered

A 525-million-year-old fossil of an extinct worm-like animal known as the Cardiodictyon catenulum was first discovered in China in 1984, but only recently have scientists found that the barely half-an-inch animal has a brain. Using a technique called “chromatic filtering,” scientists were able to reveal the animal’s nervous system and brain in an unsegmented head. Not only is this finding extremely out of the ordinary—as many believed brains were impossible to fossilize—but it also questions common assumptions about evolution. “This anatomy was completely unexpected because the heads and brains of modern arthropods, and some of their fossilized ancestors, have for over a 100 years been considered as segmented,” says Nicholas Strausfeld, a professor from the University of Arizona Department of Neuroscience, who led the study. The Cardiodictyon‘s unsegmented head and brain suggest a new theory about evolution: that the brain and trunk nervous system evolved separately. This discovery could impact the understanding of other creatures beyond arthropods, as well. Learn more about it at Interesting Engineering.

Image courtesy of Nicholas Strausfeld