“The trails that we see are actually casts, corresponding to the base of the sauropods’ feet,” Moreau explains. “It’s as if you were looking at the tracks left by the dinosaurs from below. What happened is that infiltrated water eroded the rock beneath the sedimentary layer which contains the footprints.”
https://scienceblog.com/516341/dinosaur-footprints-on-a-cave-ceiling/