The most common dinosaur fossils in the Glen Canyon Sandstone so far have been footprints, although there has been one partial skeleton discovered. Tracks present an interesting nomenclature problem because they are labeled with their own names, which are never the same as the names of the species that might have made them. This is because tracks are usually too generic-they could have been made by any similar dinosaur of a certain size. For example, the foot of Coelophysis is so similar to that of its relative Procompsagnathus that trying to distinguish between the two footprints would be almost impossible. So instead of calling a track of a certain shape and size "the one made by Coelophysis or Procompsagnathus," paleontologists simply pick an unrelated name.