elucidation time

Last night while returning from a walk to the supermarket located in downtown Bradford, PA, a number of artificially-crushed stones lying on a brightly lighted sidewalk alongside Kennedy Street appeared to have...shadow wings!  The stones are the kind often used to cover pathways, and have jagged, pointed edges that hurt the feet without study footgear.

Because Ice Age glaciers are known to have had a similar effect upon topography, the evolutionary question is, "Did pterodactlys post-date common dinosaurs?"