Its name is Pentecopterus decorahensis and it is the oldest species of sea scorpion described to date. The name originates from an ancient Greek warship called the Penteconter. Paleontologists from Yale and the University of Iowa recently made the find along the upper Iowa River.
The discovery site of the fossil itself is in a very interesting location, geologically speaking. It was uncovered in a thick shale within an ancient meteorite impact site.
The ancient sea scorpion is an eurypterid, and is categorized with modern spiders, lobsters, and ticks. This find is significant because it shows that eurypterids evolved 10 million years earlier than previously thought. The fossil is believed to be 460 million years old.
Pentecopterus decorahensis was a large predatory animal. It was more than 5 ft. long and had a unique paddle extending from its body, which it used to swim. The animal also had grasping limbs which it utilized for grabbing prey.
You can read more about the Pentecopterus decorahensis in the journal BMC Evolutionary Biology.