Ancient fossil marks bridge between early arachnids and modern spiders

 March 30, 2016 by Bob Yirka 

(Phys.org)—A team of researchers from the U.S., Germany and the U.K. has used modern technology to reveal the true nature of an ancient arachnid. In their paper published in Proceedings of the Royal Society B the team describes the ancient creature as "almost a spider."

Back in the 80's a team of researchers discovered a host of fossils in a part of what is now eastern France, but at least one of them was only partly visible because the rest of its body was encased in ironstone. Because attempting to remove the dense opaque stoneware would have destroyed the fossil, researchers simply put it in a drawer and waited for technology to develop that would allow for examining the fossil while still inside the stone. In this new effort, the researchers have used technology similar to medical CT scans to allow for creating 3D imagery of the fossil and in so doing have added another piece to the puzzle of how spiders evolved.

The fossil, named Idmonarachne brasieri was dated to approximately 305 million years ago, putting it before the dinosaurs, and it resembles modern spiders in many ways, but is missing one critical part: an organ for spinning silk. The fossil also did not have a tail-like appendage, which has been found on other arachnids of nearly the same time period, which suggested that it was a unique species, one that is believed to have gone extinct as its cousins continued to evolve into modern spiders. Because of its age and body structure, the specimen is helping scientists learn more about the manner in which spiders evolved. They believe it is one of the closet relatives without actually being a true spider. The 1.5cm arachnid was also found to have impressive jaws, which further helped prove it was a unique species.

Read more at: