Why are fossils rare in conglomerates?
Animals need to be buried under certain conditions in order to fossilize — rapid burial in a material that shuts out oxygen and predators isd best, which is why mudstones preserve the best fossils. Conglomerates start life as a mass of shingle or pebbles which is later compacted and cemented by the percolation of water. Any animal that died under these conditions would quickly decompose. However, you can find “reworked” fossils in conglometates. These are animals that died millions of years earlier, then the rocks in which they were fossilized brojke away (through erosion) and became part of a conglomerate.
