Paleontologists have analyzed the fossilized features of the brain and central nervous system of Mollisonia symmetrica, an extinct animal that lived in the mid-Cambrian seas around 508 million years ago. Their results show that Mollisonia symmetrica’s nervous system corresponds to that of living spiders and scorpions (arachnids). This discovery challenges the widely held belief that the diversification of arachnids happened only after their common...
