I browsed the entire thread earlier.
Many of the posted links are now dead but, to summarise, both the photos of US Civil War soldiers standing around a supposed downed pterosaur (the Freakylinks one and the canoe one) are confirmed hoaxes and something of a red herring.
The legendary "missing" photo that people recall seeing had a large winged creature - possibly feathered, possibly not, stretched out in front of a barn or similar building.
A brief Google, using these criteria, displays a number of photos and a few sketches.
I won't bother posting the drawings, but I assume the following photos have long since been thoroughly debunked?
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Isn't it possible that mock-ups like these have been used in cryptozoological publications and credulous readers took them at face value as genuine photos?
Let's face it, finding an extant pterosaur or even an Argentavis magnificens would be utterly fantastic - but it isn't going to happen and these magnificent creatures haven't graced our skies for millions of years.