Dinosaur dance floor is a term that geologists use to describe a 3/4-acre site of densely packed dinosaur footprints at the Vermilion Cliffs National Monument along the Arizona-Utah state line. The area contains more than 1,000 footprints which were made approximately 190 million years ago. Researchers are not sure which species made the tracks, but they did say there were 4 different kinds of tracks present at the site.