Paul Selden/Museum of Nature
The newly discovered species has distinctive spiked 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 dread, let alone encountering one with large, spiky legs.
But that’s exactly what roamed northeastern Illinois in the Late Carboniferous, about 300 million to 320 million years ago, according to a study published Friday in the Journal of Paleontology.
The newly discovered long-extinct species is described as a “large spider-like arachnid” with “distinctive large leg spikes” by the study’s authors. They were unable to place the creature in any known order of arachnids due to the specimen’s lack of mouthparts, which scientists use to classify them.
“You see sort of spiny legs in some arachnids, but we’ve never seen one that really has these big spines all the way through, at least the first parts of the legs. It’s very, very striking,” Dr. Jason Dunlop, curator of arachnids and millipedes at the Museum of Natural History in Berlin and co-author of the study, told CNN on Friday.
“We looked at it twice and were like, ‘What are we looking at here?’
Fossil preparation expert Bob Masek first discovered the specimen in the 1980s in fossils preserved at the Mazon Creek Lagerstätte in Illinois. (The German word is a term paleontologists use to describe an exceptional site with many perfectly preserved fossils.) However, it was not until 2023 that it became clear that the specimen was a newly discovered species and fossil collector David Douglas, who had acquired it from Masek, donated it for research.
The researchers then examined and photographed the fossil using a camera attached to a microscope.
They found that the creature was “clearly something very different from any previously described arachnid”, with spiny legs that resembled some modern reaper arachnids, but with a different body type.
Paul Selden/Museum of Nature
Scientists believe that the spiny legs were for defensive purposes.
The creature probably used its spines for defensive purposes, not to attack other animals, like hedgehog spines do today, Dunlop said.
“That means if something tries to bite it, it grabs the spines in its mouth. … We’re talking about processing time, which means if you want to eat something prickly, it takes longer because you have to break off the spines or bite off the bits that don’t have spines,” he added.
“We can assume there were scorpions and other spiders around,” Dunlop said, as well as primitive lizards or large amphibians that would have hunted these arachnids, but it’s impossible to know for sure.
Without the mouth apparatus, the researchers can’t determine its closest relative, but suggest it may belong to a wider group that includes spiders, whip spiders and whip scorpions.
Paleontologists have so far only found this particular species in North America, but it could “occur somewhere else” in northern Europe as well, Dunlop said.
“A huge area in much of what is now Europe and North America was probably a kind of giant rainforest, and wherever coal is found today, you have 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 honors the Douglas family, who donated the specimen to the Chicago Field Museum of Natural History, and the species name refers to the spines that make this arachnid so distinctive.
