Six-Foot-Long Predatory Scorpion Terrorizes Iowa

Correction: The six-foot-long predatory scorpion is not currently terrorizing Iowa. But it used to, about 467 million years ago, back when Iowa was an ocean.

While excavating a meteorite crater in northeastern Iowa’s Winneshiek Shale, paleontologists discovered the fossil of an enormous and bizarre ancient scorpion species that lived in the ocean. It is now believed to be Planet Earth’s earliest large predator. The findings were published in the journal BMC Evolutionary Biology on August 31st, 2015.

“Tick…I Am Your Father” – Darth Pentecopterus

Researchers named the new-old species Pentecopterus decorahensis after its many-legged body’s resemblance to an ancient Greek war ship, the pentecopter. (“Decorahensis” presumably means something like “really badass,” or “utterly terrifying,” or “we named it after a ship but it’s actually a six-foot-long f***ing sea-scorpion.”)

The Pentecopterus isn’t the first species of aquatic, ancient scorpion to be discovered, nor—terrifyingly—is it the biggest. It joins a roster of other eurypterids, an extinct genus of arthropods that are the ancestors of modern-day arachnids, like spiders and ticks. Arthropods are a phylum of invertebrate animals with segmented bodies, jointed appendages, and exoskeletons; insects, crustaceans, arachnids, centipedes, and millipedes. However, eurypterids are the largest arthropods to have ever existed. Their remains have been discovered across the globe.

Godzilla vs. Mechagodzilla Pentecopterus vs. Jaekelopterus

The largest eurypterid ever discovered is the truly terrifying Jaekelopterus rhenaniae, unearthed in Germany in 2007, measuring 8.2 feet long. Similarly to the Pentecopterus, it terrorized shallow waters, preying on fish, crustaceans, and other eurypterids. But it had two key differences: one, the Jaekelopterus lived in fresh water, invalidating the common moniker “sea scorpion” for all eurypterids (Don’t make that mistake again!). Two, more importantly, the Jaekelopterus is quite young, a mere 390 million years old. The earlier glory days of the Pentercopterus, about 467 million years ago, extends previous estimates of how long eurypterids ruled Earth’s waters.

What Could Have Vanquished Such Glorious Creatures?

Why, none other than the Permian-Triassic extinction event 252 million years ago, the planet’s most severe extinction. The dinosaurs were just the highest-profile casualty of this event (possibly a meteor impact, possibly a volcanic event, theories abound), which wiped out 70% of all terrestrial species and 96% of all marine species. (Read those numbers again.)

It took at least 10 million years for life to recover to pre-event levels. If catastrophe hadn’t struck, I could have been a super-intelligent Pentecopterus, writing this article right now, about how my species wiped out the dim-witted Jaekelopterus 252 million years ago with cunning technological warfare.

Pentecopterus Is “Incredibly Bizarre,” Says Scientist Whose Job Is Studying Incredibly Bizarre Things

James Lamsdell, the study’s lead author and researcher from Yale University, could not stress enough how strange this creature is.

“The new species is incredibly bizarre,” he said in a statement. “The shape of the paddle—the leg which it would use to swim—is unique, as is the shape of the head. It’s also big—over a meter and a half long.”

He goes on: “Perhaps most surprising is the fantastic way it is preserved – the exoskeleton is compressed on the rock but can be peeled off and studied under a microscope. This shows an amazing amount of detail, such as the patterns of small hairs on the legs. At times it seems like you are studying the shed skin of a modern animal – an incredibly exciting opportunity for any paleontologist.”

These giant, hairy, crabby, ancient scorpions are no longer with us, for better or worse. But now, thanks to being dug out of the ground and preserved on microscope slides and computer-generated images, they are getting the honor they deserve.

For now, Iowa is safe. But watch out: I’m in a bidding war with some award-winning filmmakers for the movie rights to Eurypterid Park.

Who wins: Pentecopterus vs. Jaekelopterus? Share your thoughts about these scorpion species!


The six-foot scorpion predator sounds scary. Here’s Musio to bring you back to your happy place:

Kerry Martin is a semi-native of Denver. He went to school in Vermont for its great beaches. Now transplanted to Brooklyn, he works as a volunteer coordinator/community organizer for ArchCare TimeBank when he isn't writing Ecology, Technology, and Offbeat articles for Clapway.