By Ed Payne
(CNN) - In the prehistoric oceans, this was one bad bug.
Scientists are marveling at the world's oldest sea scorpion -- the Pentecopterus, named after a Greek warship.
Imagine a creature nearly 6 feet in length, with a long head, a narrow body and large limbs for grasping and trapping prey.
It was part of the eurypterid family, a group of ancient creatures that are the ancestors of modern spiders, lobsters and ticks.
"Pentecopterus is large and predatory, and eurypterids must have been important predators in these early Palaeozoic ecosystems," said James Lamsdell with Yale University, who was the lead author of a study about the creature.
These sea scorpions lived some 467 million years ago but weren't discovered until 2010 in a fossil bed by the Upper Iowa River in northeastern Iowa.
Geologists with the Iowa Geological Survey at the University of Iowa found them in a meteorite carter. Yale scientists are helping them analyze the find.
The study appears in Tuesday's online edition of the journal BMC Evolutionary Biology.
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