Scientists discover ancient six-foot-long sea scorpion

IOWA CITY, Iowa, Sept. 1 (UPI) -- Scientists say they've discovered one of the first really big predators to prowl Earth. It was a giant scorpion. But it didn't hunt the desert sands. It was a sea scorpion, and it measured nearly six feet long.

Like the beginning of a comic book superhero, the scorpion was discovered by paleontologist in an ancient meteor crater in Iowa. The creature is estimated to be more than 460 million years old.

Dubbed Pentecopterus, after a Greek warship, by Yale researchers, the creature is a member of an extinct group of arthropods called eurypterids. The group is closely related to arachnids, the class of invertebrates that includes spiders and scorpions.

The new species was described in the latest issue of the journal BMC Evolutionary Biology.

"This shows that eurypterids evolved some 10 million years earlier than we thought, and the relationship of the new animal to other eurypterids shows that they must have been very diverse during this early time of their evolution, even though they are very rare in the fossil record," lead study author James Lamsdell, a postdoctoral associate at Yale University, said in a press release. "Pentecopterus is large and predatory, and eurypterids must have been important predators in these early Palaeozoic ecosystems."

Researchers say the species specialized in hunting shallow marine waters that were likely brackish in nature, low in salinity and oxygen, making them inhospitable to other more common ancient marine animals. Scientists say the predator likely hunted fish and other smaller invertebrates.

It's heyday stretches across the period of the Paleozoic Era known as the Ordovician period, from 485 to 444 million years ago, which followed the Cambrian explosion.

"The undisturbed, oxygen-poor bottom waters within the meteorite crater led to the fossils' remarkable preservation," said lead excavator and study co-author Huaibao Liu, a paleontologist with the Iowa Geological Survey and the University of Iowa. "So this discovery opens a new picture of the Ordovician community that is significantly different from normal marine faunas."