An article published in the journal “Scientific Reports” illustrates the identification of the oldest known scorpion species, which lived about 437 million years ago, in the Silurian period. A team of researchers named it Parioscorpio venator after examining fossils discovered in a quarry in Wisconsin in 1985. This species had some anatomical features that are practically identical to those of modern scorpions but the most interesting discovery is in the respiratory structures that indicate that it could live on the mainland. This is the oldest evidence that an animal could survive out of the sea and indicates that at the time at least a part of arachnids had already colonized the mainland.