Was the First Terrestrial Animal a Scorpion?

In America, the fossil of a scorpion that could breathe on land more than 400 million years ago has been found.

Which was the first animal to walk on land and breathe atmospheric oxygen, kicking off the ocean exit and colonizing the planet? The answer is a fossil that for 35 years has been locked in a drawer at the Geology Museum of the University of Wisconsin, recently rediscovered by Otterbein University paleontologist Andrew Wendruff, who published his study in Scientific Reports. The animal, named Parioscorpio venator, is a small scorpion just over 2 centimeters long that lived during the Silurian, 437 million years ago, in present-day Wisconsin: its anatomy suggests that it was an animal capable of living both underwater and outdoors.


The Parioscorpio fossil (indeed, the fossils, since two have been found) is particularly interesting because it has hybrid characteristics between its aquatic ancestors and its terrestrial descendants. From the first, for example, the animal takes the eyes (composite and forward-facing, as in modern crustaceans), while it has in common with the latter the presence of a sting and, above all, a series of “tubes” that connect its circulatory apparatus with that respiratory system – an indication of its ability to absorb oxygen from the air, otherwise called “breathing on land”. The same structures, Wendruff explains, are found in another primitive arthropod, the limulus, which is also capable of amphibious life.