Why are fossils typically found only in sedimentary rocks?

Fossils are primarily found in sedimentary rocks because these rocks form from the accumulation and cementation of sediment, which can quickly bury organisms upon death. This rapid burial is crucial for fossilization, as it protects the organism's remains from decomposition and scavengers.12

Sedimentary rocks are formed at the Earth's surface through processes like deposition by water, wind, or ice, or from the secretions of organisms. This environment is conducive to preserving the hard parts of organisms, such as bones and shells, which are most likely to fossilize. In contrast, igneous rocks form from molten material at high temperatures, and metamorphic rocks are altered by heat and pressure, conditions that would destroy fossil evidence. Therefore, the gentle depositional environment of sedimentary rocks offers the best chance for the preservation of ancient life.312