A limestone wall covered with preserved dinosaur tracks was discovered in 1994 near a cement factory in southern Bolivia. Four years later, when a team of scientists led by a famed Swiss paleontologist was able to visit, the wall was named “the largest site of dinosaur tracks found so far.”

It’s unclear how the wall, called Cal Orcko, went undiscovered for so long, as it is filled with more than 5,000 tracks made during the second half of the Cretaceous period about 68 million years ago. There are so many tracks, actually — and they’re placed in such strange patterns — that some scientists refer to the area as a “dinosaur dance floor.”

So far, six different types of dinosaur prints have been identified. One special track that measures 347 meters is the longest dinosaur trackway ever discovered and was made by a baby Tyrannosaurus rex nicknamed “Johnny Walker” by some of the local researchers.

Eight other limestone walls with dinosaurs tracks have been found in the region. Millions of years ago, when dinosaurs walked the earth, this area was part of a huge shallow lake. The tectonic plate shifts during the Tertiary period that formed the great Andes Mountains also pushed some of these limestone walls out from the bed of the lake. The rock cliff measures about 325 feet tall and juts into the sky at a 70 degree angle.