The reason we find fossils in some places and not in others has a lot of factors. For one the chance of fossilization is incredibly rare, everything in the environment has to be right for it to occur. Next, after the remains have been fossilized underground, they have to be lifted back to the surface through tectonic activity or through erosion. I’ve worked with a lot of mining geologists that have shown me pictures of dinosaur footprints found way underground. This is a picture of some dino tracks found in a mine in Australia in the 1950s. Just imagine how many wonderful finds are hundreds of feet below us that will never be seen.
Photo by Anthony Romilio from ABC Australia