Pentecopterus: a Giant Darriwilian Ordovician Sea Scorpion From 10 Million Years Earlier Than Expected

You don't name a sea creature after an ancient Greek warship unless it's built like a predator.

That's certainly true of the recently discovered Pentecopterus, a giant sea scorpion with the sleek features of a penteconter, one of the first Greek galley ships. A Yale University research team says Pentecopterus lived 467 million years ago and could grow to nearly six feet, with a long head shield, a narrow body, and large, grasping limbs for trapping prey. It is the oldest described eurypterid -- a group of aquatic arthropods that are ancestors of modern spiders, lobsters, and ticks.

A detailed description of the animal appears in the Sept. 1 online edition 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," said James Lamsdell, a postdoctoral associate at Yale University and lead author of the study.

"Pentecopterus is large and predatory, and eurypterids must have been important predators in these early Palaeozoic ecosystems," Lamsdell said.

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