Fossil Shows Sea Scorpions Stretched to 8 Feet

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Things were tough in the Paleozoic Era. Violent storms, dramatic changes in oxygen levels, not much dry land — and in the water, there were giant, carnivorous sea scorpions.

Scientists knew these creatures were big. Now they've found a fossil from the biggest sea scorpion yet.

Four-hundred million years ago was a bad time to go swimming. There were a lot of predators. Erik Tetlie, a paleontologist at Yale, said sea scorpions were the scariest.

"They kind of looked like a flattened submarine," Tetlie said. "Then they had these massive claws in front which could be up to a meter long. And then they have five pairs of legs, and the last of these were the swimming legs, which were flattened paddles" — kind of like a lobster big enough to play in the NBA.

Scientists call the sea scorpions "eurypterids," and Tetlie said even their fossils are intimidating.

"My supervisor in Bristol used to say that he would rather be in a pool with a shark than in a pool with a eurypterid, and I think I would agree with that," he said.

Tetlie and his former boss are part of an international team reporting on a new fossil that is likely to enhance the sea scorpion's frightening reputation. The fossil came from a quarry in Germany. It is part of a claw, and it is about 18 inches long. The creature it came from was probably 8 feet long — a record.

Tetlie said giant sea scorpions apparently led a simple life.

"They probably ate primitive fish, other smaller sea scorpions, whatever they can get their claws into," he said.

But unlike modern scorpions, they did not kill their prey with a poison stinger.

"They would probably just sort of sink their fangs into it and start munching away," he said.

Lorenzo Prendini, a scorpion expert at the American Museum of Natural History in New York, said eurypterids did not need a stinger to subdue their prey.

"The spines on the claws would have inflicted a lot of damage," Prendini said. "They may have even ripped them apart with the claws. But I think a combination of that and the actual jaws, which are quite well developed, with fanglike structures, would have done the damage."

Sea scorpions had their tender moments, too – like when thousands gathered in the shallow water to shed their outer skeletons and mate.

About 255 million years ago, the sea scorpions disappeared.

One factor might have been a decrease in the amount of oxygen in the oceans, but Prendini thinks they just got eaten — when something even bigger and meaner evolved.

"There were certainly some enormous dinosaur relatives of the day — ichthyosaurs and the like. I think they would have made short work of these guys," he said.

Survivors might have become smaller and ended up on land — though the fossil record isn't entirely clear on that.

"Modern scorpions are more closely related to other arachnids, like spiders and mites and a host of other peculiar creatures, than they are to the sea scorpions, but all of them shared a common ancestor at some point in time," Prendini said.

As for the giant sea scorpion, it is still a big deal in places like New York — where it is the official state fossil.

The new finding is described in the current issue of the journal Biology Letters.

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