Scientists Discover Fossil of Giant Terrifying ‘Sea Scorpion’

by Jon D. B.

These massive arthropods were over a meter long, with this new fossil packing some serious mandibles and claws to snatch up marine prey.

Take a blacklight out into the desert and you may see little alien creatures glowing as if they’re radioactive. But they’re not aliens or nuclear mutants – they’re scorpions. These amazing predatory arachnids has fascinated – and plagued – mankind for as long as we’ve been around. They’re ancient, and their anatomy is such an effective killing machine that many other species would evolve to a similar state over the eons.

One such creature has just come to light in China’s Xiushan Formation. Paleontologists are calling it a “sea scorpion” – and its remains show a true fossil sea monster.

Meet Terropterus xiushanensis, an enormous arthropod that stalked the seas off China’s coast around 435 million years ago. In life, these aquatic predators would’ve been over 3-feet-long (1 meter). Our modern, small scorpions are terrifying enough. But a 3-foot one? Pass.

“Eurypterids, or sea scorpions, are an important group of mid-Paleozoic chelicerate arthropods whose evolution and paleoecological significance have also attracted much attention in recent years,” says Professor Bo Wang of Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences. Wang is the discovering project‘s lead and designer, and has a soft spot for these amazing fossil “sea scorpions.”

“Their second, and especially the third, pair of prosomal limbs are enlarged and very spiny. These limbs were presumably used for prey-capture, and analogies can also be drawn with the ‘catching basket’ formed by the spiny pedipalps of whip spiders among the arachnids,” Wang continues of the beast.

Fossil of Monster ‘Sea Scorpion’ is Only 1 of 4 Mixopterus Specimens

Fossil tracks of Eurypterid dinosaurin 400 million-year-old sandstone. Z-bend, Murchison River, Kalbarri National Park, Western Australia. (Photo by Auscape/Universal Images Group via Getty Images)

“Our knowledge of these bizarre animals is limited to only four species in two genera described 80 years ago, however: Mixopterus kiaeri from Norway, Mixopterus multispinosus from New York, Mixopterus simonsoni from Estonia, and Lanarkopterus dolichoschelus from Scotland,” Wang cites.

With such a rarity, this new fossil find is a dazzling one.

“One of the most remarkable eurypterid families is Mixopteridae, whose members are quite large and superficially scorpion-like eurypterids bearing highly specialized anterior appendages,” Wang says of the new species’ cousins.

The family of Euryptids is the largest arthropods to exist in history. And while the new Terropterus xiushanensis was large at 3-feet, its cousin, Jaekelopterus, was a staggering 8-feet-long (2.5 meters).

To get a much better feel for these fossil sea terrors, PBS’s fantastic EONS shorts also holds an expose on “sea scorpions”:

Sea scorpions thrived for 200 million years, coming in a wide variety of shapes and sizes. Over time, they also developed a number of adaptations–from crushing claws to flattened tails for swimming. And some of them adapted by getting so big that they still hold the record as the largest arthropods of all time.