Mar 31, 2016

305-Million-Year-Old Fossil a Window on Spider Evolution

An international team of researchers has examined a 305-million-year-old, not-quite-a-spider fossil that could shed light on the early evolutionary origins of modern-day spiders.

The new, extinct species, dubbed Idmonarachne brasieri, was found in France in the 1980s, according to PhysOrg, but the fossil was partly encrusted in stone, so full examination wasn’t possible until modern 3D scans gave scientists a closer look without risking damage to the specimen.

“Our new fossil occupies a key position in the evolution of spiders,” said the study’s lead author Russell Garwood, of the University of Manchester, in a press release.

“It isn’t a true spider,” said Garwood, “but has given us new information regarding the order in which the bits of the anatomy we associate with spiders appeared as the group evolved.”

The reason it’s not a “true” spider, the researchers say, is because the ancient almost-spider lacked spinnerets, the special appendages modern spiders use to spin silk.

“Our creature probably split off the spider line after [Attercopus], but before true spiders appeared,” Garwood told the BBC.

“This fossil is the most closely related thing we have to a spider that isn’t a spider,” Garwood added – a creature about six-tenths of an inch long (1.5 millimeters), with legs and a jaw that were like those of spiders, just without the spinneret.

Garwood and his team’s work was published today in the journal Proceedings of the Royal Society B.

From Discovery News

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