Somewhere in South America, there are dinosaur footprints in solid rock. I can only assume they were preserved by volcanic eruptions..................
Probably mud on the side of a river that got covered up.
The path behind my house in Israel has Roman (or Greek or someone in a different style shoe than native) that got covered in mud and turned to almost stone. We made plaster casts since we had uncovered them by moving flagstones, so the local uni said they were not long for this world.