Pterygotus pennsylvanicus

The sea Scorpion

The Eurypterids were chalicerate, ( biting claws ) Arthropods that diversified into a variety of sizes and shapes. Pterygotus from the Silurian era pictured here was one of the largest at around six feet long. New discoveries in Britain have revealed a Eurypterid pushing eight feet in length.

The body of Pterygotus shows that it was an aggressive predator; large eyes to detect movement, enormous spined claws that could crush and bring prey towards the mouth, definitely not for picking flowers. Abundant Prey species in the form of armored trilobites and ostracoderm ( bony skin ) fishes during the Silurian meant that a lot of crushing was needed to get the soft stuff into Pterygotus' small mouth.

Just behind the eight small walking legs were large flattened paddles, which are believed to have had a swimming function. The paddles may have been used to "row" through the water somewhat like water boatmen and backswimmer bugs of today.

The broad tail of Pterygotus ended in a large rounded paddle with dorsal keels. The tail could flex up and down and may have been the best bet for Pterygotus to cover a distance or make a quick getaway. But being one of the larger predators of the Silurian lagoons, Pterygotus probably caused more fleeing than anything else.