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Ancient arachnid was almost a spider

Fossil is missing organs needed to spin silk

7:05pm, March 29, 2016
3-D reconstruction of ancient arachnid

SPIDERLIKE  The ancient arachnid Idmonarachne brasieri was a close cousin of spiders. Researchers used CT scans to create a 3-D visualization of the 305-million-year-old fossil. 

A 305-million-year-old arachnid might shed some light on spider evolution.

Researchers discovered the fossilized remains of Idmonarachne brasieri curled up in ironstone from central France. The legs, mouthparts and body of the 1-centimeter-long arachnid were all spiderlike. But the ancient arthropod was missing a key feature of all true spiders: silk-spinning organs.

I. brasieri also lacked a tail-like appendage found on known arachnid ancestors that lived at the same time, during the late Carboniferous period. The new species was part of a previously unknown group of ancient arachnids that could help scientists suss out how and when spiders and their cousins evolved, the team reports March 30 in Proceedings of the Royal Society B.

The team chose the creature’s moniker, Idmonarachne, to reflect its close relationship with its web

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