A recent discovery by paleontologists working in France may offer key new insights into the origin of one of the world’s most feared critters. According to a report from National Geographic, the ancient arachnid lived roughly 305 million years ago and is likely one of the species that gave rise to modern spiders.
The creature, named Idmonarchne brasieri, is one of the earliest known silk weaving invertebrates. It was discovered by amateur fossil hunter Daniel Sotty in Montceau-les-Mines in eastern France, and placed in the archives of the Muséum National d’Histoire Naturelle in Paris.
According to Russel Garwood, a paleontologist from the University of Manchester in the U.K., “When I first saw it, I was unsure what kind of arachnid it was. The legs and entire front half of the body was buried in the rock.”
Garwood and a team of researchers recreated the body of the ancient arachnid in a 3-D model that revealed stunning similarities to present-day spiders. For example, the ancient arachnid shares the characteristic sharp fangs of many spiders alive today.
But the model revealed that present day spiders have also changed quite a bit since the days of Idmonarachne. Its abdomen is segmented, much like older forms of arachnids like pseudoscorpions.
Perhaps most interesting clue derived from the fossil is that ancient arachnids may not always have had the ability to spin webs. Idmonarachne lacked spinnerets, the organs used to carefully weave their silk into a deadly trap.
Much like another spider relative, urareneids, Idmonarachne likely used its silk to line their burrows within the ground or to secure egg sacks.
Despite the differences between Idmonarachne and more modern species of spiders, scientists are confident that the creature is a relatively close ancestor to the arachnids we see on Earth today. Evolution would come to favor those arachnids that were skilled in trapping prey in elaborate webs, but ancient arachnids seem to have once ruled the world.
The study, published in the Proceedings of the Royal Society B, can be found here.