China’s Ancient Spider Fossil Deemed a Hoax, Unmasked as a Crayfish

Earlier this year, a remarkable new fossil specimen was unearthed in the Lower Cretaceous Yixian Formation of China by area fossil hunters — possibly a huge ancient spider species, as yet unknown to science.   (Image: via   pixabay  /  CC0 1.0)
Earlier this year, a remarkable new fossil specimen was unearthed in the Lower Cretaceous Yixian Formation of China by area fossil hunters — possibly a huge ancient spider species, as yet unknown to science. (Image: via pixabay / CC0 1.0)

Earlier this year, a remarkable new fossil specimen was unearthed in the Lower Cretaceous Yixian Formation of China by area fossil hunters — possibly a huge ancient spider species, as yet unknown to science.

The locals sold the fossil to scientists at the Dalian Natural History Museum in Liaoning, China, who published a description of the fossil species in Acta Geologica Sinica, the peer-reviewed journal of the Geological Society of China. The Chinese team gave the spider the scientific name Mongolarachne chaoyangensis.

The specimen will be stripped of the scientific name Mongolarachne chaoyangensis and rechristened as a crayfish. (Image: Selden et al)

The specimen will be stripped of the scientific name Mongolarachne chaoyangensis and rechristened as a crayfish. (Image: Selden et al)

But other scientists in Beijing, upon seeing the paper, had suspicions. The spider fossil was huge and strange looking. Concerned, they contacted a U.S. colleague that specializes in ancient spider fossils. Paul Selden, distinguished professor of invertebrate paleontology in the Department of Geology at the University of Kansas, Selden said:

Selden and his colleagues at KU and in China (including the lead author of the paper originally describing the fossil) recently published an account of their detective work in the peer-reviewed journal Palaeoentomolgy. Selden said:

In possession of the original fossil specimen at KU, Selden teamed up with his graduate student Matt Downen and with Alison Olcott, associate professor of geology. The team used fluorescence microscopy to analyze the supposed spider and differentiate what parts of the specimen were fossilized organism, and which parts were potentially doctored. Selden said:

The team’s application of fluorescence microscopy on the fossil specimen showed four distinct responses — regions that appear bright white, bright blue, bright yellow, and ones that are dull red. According to the paper, the bright white areas are probably a mended crack. The bright blue is likely from mineral composition of the host rock.

specimen of fossilized crayfish (Cricoidoscelosus aethus) from the Yixian Formation preserved in a similar manner to Mongolarachne chaoyangensiss. (Image: Selden, et al)

Specimen of fossilized crayfish (Cricoidoscelosus aethus) from the Yixian Formation preserved in a similar manner to Mongolarachne chaoyangensiss. (Image: Selden, et al)

The yellow fluorescence could indicate an aliphatic carbon from oil-based paint used to alter the crayfish fossil. Finally, the red fluorescence probably indicates the remnants of the original crayfish exoskeleton. The KU researcher said:

Selden said that in the world of fossils, fakery is commonplace, as impoverished fossil hunters are apt to doctor fossils for monetary gain. What’s less common, he said, was a fake fossil spider, or a forgery making its way into an academic journal.

Image A shows a mosaic of parts of the specimen as seen under fluorescence microscopy: bright white shows areas of cement used to repair the specimen, bright blue shows the rock matrix, bright yellow marks areas painted with oil-based paint, and dull red is the fossil cuticle. (Image: Selden, et al)

Image A shows a mosaic of parts of the specimen as seen under fluorescence microscopy: bright white shows areas of cement used to repair the specimen, bright blue shows the rock matrix, bright yellow marks areas painted with oil-based paint, and dull red is the fossil cuticle. (Image: Selden, et al)

However, he acknowledged the difficulty of verifying a fossil and admitted he’d been fooled in the past, saying:

Selden didn’t know the eventual fate of the enhanced spider fossil, which he likened to the famed “jackalope.” He said he thought it would go back to China where it could be put on display as a cautionary tale. One thing is for certain: It will be stripped of the scientific name Mongolarachne chaoyangensis and rechristened as a crayfish.

a map of specimen showing cracks, cemented areas (grey), and painted parts (brown); Lower left, detail of an area near where the posterior (false) legs meet the body, showing bright yellow fluorescence (= paint) with brush strokes overlying dull red cuticle and blue matrix. (Image: Selden, et al)

A map of the specimen showing cracks, cemented areas (grey), and painted parts (brown); lower left, detail of an area near where the posterior (false) legs meet the body, showing bright yellow fluorescence (= paint) with brush strokes overlying dull red cuticle and blue matrix. (Image: Selden, et al)

Because of the fossil’s alterations and state of preservation, Selden said it was hard to pin down its exact species. The team tentatively placed the fossil in Cricoidoscelosus aethus “because this is marginally the commoner of the two crayfish recorded from the Yixian Formation.”

Provided by: Brendan M. Lynch, University of Kansas [Note: Materials may be edited for content and length.]

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