American scientists from Iowa University have found a prehistoric sea scorpion thought to be related to five-foot spiders. The researchers published their findings on the extinct creature they found nearly five years ago in the BMC Evolutionary Biology Journal.

The human-sized creatures have been given the scientific name, Pentecopterus decorahensis - in honor of a war galley used in Ancient Greece.

Like Us on Facebook

The Pentecopterus existed almost 500 million years ago and could reach around two meters in length. Classified as animals having an exoskeleton, their descendents are the modern day lobsters and spiders as well as ticks.

Scientists considered them to be the oldest eurypterid discovered. Head of the study group, James Lamsdell said the discovery shows that the sea scorpions evolved more than ten million years earlier than what was generally known.

The giant sea scorpion was a predator during the Palaeozic era, according to Lamsdell.

University of Iowa scientists stumbled upon the fossils in 2010 and have studied them together with their colleagues from Yale University. The scientists were impressed with the fossils' state of preservation, which includes both mature and young specimens.

Derek Briggs, a paleontologist and one of the study's lead researcher said the fossils were discovered in a part of the river that was also the site of a five kilometer wide meteor impact millions of years ago. Aside from the Pentecopterus, other prehistoric marine life and plants have also been discovered. The geologist, who led the dig, Huaibao Liu said the discovery of various Ordovician-era creatures and plants have deepened their understanding of that time period.

Based on the fossils gathered, scientists have surmised that the sea scorpion might have used six of its limbs for walking. The last pair of its limbs in its rear may have been used to dig in the sea floor or to swim. To get hold of its victims, the Pentecopterus possibly used the first two pairs of its limbs. Its rear "legs" has hard fibers which may have been used to get a better feel its surroundings.

Tagssea scorpion, pentecopterus, eurypterid, james lamsdell, palaeozic era, prehistoric creatures, Pentecopterus decorahensis, Prehistoric sea scorpion