‘The closest thing to a spider that isn’t a spider’ discovered

30 Mar 2016

Researchers have discovered a 305m-year-old fossil that predates the dinosaurs and appears to be similar to modern spiders, but not quite.

A rock dug up in France in the 1980s has only now revealed the fossilised remains of a now-extinct species of arachnid that has been dubbed ‘almost a spider’.

Named Idmonarachne brasieri, the discovery is one of the more revealing archaeology finds in recent years, adding an entirely new strand of arachnids, dating from before the dinosaurs, and showing a strict deviation from modern spiders.

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The idmonarachne brasieri lived alongside better-known arachnids 305m years ago, with one of the authors of the a new paper on the find, Russell Garwood saying: “This fossil is the most closely related thing we have to a spider that isn’t a spider.”

CT scan of the fossil, published in a paper with the wonderful title ‘Almost a spider’

CT scan of the fossil, published in a paper with the wonderful title ‘Almost a spider’

The ‘non-spider’ is like modern arachnids but it’s lacking any silk-spinning capabilities. It also features notable jaws, and lacks a type of tail that has been found in similar species from the time.

The tail-like appendage features in spider fossils dating as far back as 380m years. The differences suggest this was an entirely unique species, one which has been completely wiped out as rivals evolved into today’s spiders.

The reason it took this long to discover is the find was part of a larger haul, and most of the fossil was hidden from view behind ironstone. It was impossible to reveal the full fossil without damaging it, so it was left in storage until technology caught up.

So now, rather than carving the rock, CT scans were made, resulting in detailed imagery of what the idmonarachne brasieri looked like.

“We’re looking at a line of spider-like arachnids that haven’t survived but must have split off before 305m years ago,” Garwood told Live Science.

Main spider image via Shutterstock

Gordon Hunt was a journalist with Silicon Republic