Paul Selden/Museum of Natural History
The newly discovered species has distinctive spiny legs.
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The idea of unexpectedly coming face to face with a spider-like creature is enough to fill any arachnophobe with horror, let alone encountering a creature with large, spiky legs.
However, according to a study published Friday in the Journal of Paleontology, that’s exactly what roamed what is now northeastern Illinois during the late Carboniferous period, about 300 to 320 million years ago.
The newly discovered, long-extinct species is described by the study authors as a “large spider-like arachnid” with “distinctive large spines on its legs.” They couldn’t assign the creature to any known order of arachnids because the specimen didn’t have mouthparts, which scientists use to classify it.
“In some arachnids you see sort of spiny legs, but we’ve never seen one that really has these big spines all the way through, at least not in the first parts of the legs. It’s very, very noticeable,” said Dr. Jason Dunlop, curator of arachnids and myriapods at the Berlin Museum of Natural History and co-author of the study, told CNN on Friday.
“We looked at it twice and said, ‘What are we seeing here?'”
Fossil preparation expert Bob Masek first discovered the specimen in the fossil beds of the Mazon Creek deposit in Illinois in the 1980s. (The German word is a term paleontologists use to describe an extraordinary place with many perfectly preserved fossils.) However, it was not until 2023 that the specimen was discovered to be a newly discovered species, and fossil collector David Douglass, who acquired it from Masek, donated it to research.
The researchers then examined and photographed the fossil using a camera connected to a microscope.
They found that the creature was “obviously quite different from any previously described arachnid,” with spiny legs that resembled some modern harvestman arachnids but a different body type.
Paul Selden/Museum of Natural History
Scientists believe that the spiny legs served defensive purposes.
The creature likely used its spines for defensive purposes rather than to attack other animals, similar to the spines of a modern-day hedgehog, Dunlop said.
“That means if something tries to bite it, it catches itself on the spines in its mouth. … We’re talking about processing time, meaning if you want to eat something with spines, it takes longer because you have to break off the spines or bite off the pieces that don’t have spines,” he added.
“We can speculate that there were scorpions and other spiders nearby,” Dunlop said, as well as primitive lizard-like animals or large amphibians that would have preyed on these arachnids, but there is no way to know for sure.
Without the mouthparts, researchers can’t pinpoint its closest relative, but they suspect it may belong to a larger group including spiders, whip spiders and whip scorpions.
Paleontologists have only found this particular species in North America, but it could also appear “elsewhere” in northern Europe, Dunlop said.
“A huge area of what is now Europe and North America was probably some kind of vast tropical rainforest, and wherever coal is found today there is a reasonable chance of finding these fossils (of arachnids, plants and insects),” he added .
Ultimately, the researchers named the species Douglassarachne acanthopoda. The genus name is a tribute to the Douglass family, who donated the specimen to the Field Museum of Natural History in Chicago, and the species name refers to the spines that make this arachnid so distinctive.