Fake spiders and paleontological forgery

A paper by paleontologist Paul Selden in Paleoentomology describes an interesting case of paleontological forgery: “The supposed giant spider Mongolarachne chaoyangensis, from the Cretaceous Yixian Formation of China, is a crayfish”. I found the story from a news piece by Michelle Star, who gives a layperson’s background to the case: “A Fossil Spider Discovery Just Turned Out to Be a Crayfish With Some Legs Painted On”.

"These things are dug up by local farmers mostly, and they see what money they can get for them," Selden explained.
"They obviously picked up this thing and thought, 'Well, you know, it looks a bit like a spider.' And so, they thought they'd paint on some legs - but it's done rather skilfully. So, at first glance, or from a distance, it looks pretty good.
"It's not until you get down to the microscope and look in detail that you realise there are clearly things wrong with it. And, of course, the people who described it are perfectly good palaeontologists - they're just not experts on spiders."

The article discusses how such forgeries are becoming increasingly common as a part of the fossil trade to private collectors.