Washington, September 02 (QNA) - US researchers have discovered earth's largest extinct sea scorpion, estimated to be 460 million years old, after analysing many fossils excavated in Iowa.

Iowa Geological Survey researchers discovered the fossils under the Upper Iowa River. They said the giant sea scorpion, named Pentecopterus decorahensis, was earth's first ever giant predator. The pentecopterus lived in the Ordovician period when much of Northern America was under water.

The scientists accurately determined how the predator looked through carbon dating analysis. The scorpion had a dozen massive clawed arms emerging from its head and a giant spiked tail that towered above it. At 1.83 meters long, it was the largest creature.

Yale geologist James Lamsdell, author of the study published in the journal BMC Evolutionary Biology said, "This is the first real big predator. It was a big angry bug." The pentecopterus' large legs were covered with hairs to sense their environment while their claws were used for both walking and swimming. Its forward facing front limbs were used for grabbing prey.

The well-preserved fossils, including their hard exoskeleton impressed experts he said. "At times it seems like you are studying the shed skin of a modern animal, an incredibly exciting opportunity for any palaeontologist," Lamsdell said. (QNA)