Why fossils of organisms (let’s say dinosaurs) found in rocks take the vertical space of rocks that supposedly formed over not decades, but hundreds, thousands years?

Question

Were they simply just lying on the ground for so long, undisturbed by scavenger animals, wind and water?

In: 4

Answer 1

Often they were quickly buried in mud and sediment that then took thousands of years to fuse into the sedimentary rock we find them in today.
So yes, in a sense they were just sitting there fit hundreds and thousands of years untouched by scavengers mostly because scavengers couldn’t find them buried in the mud.