AP BIOLOGY

Detailed explanation-1: -How do fossils form? Fossils are typically found in sedimentary rocks and occasionally some fine-grained, low-grade metamorphic rocks. Sometimes the fossils have been removed, leaving moulds in the surrounding rock, or the moulds may have later been filled by other materials, forming casts of the original fossils.

Detailed explanation-2: -Fossils are more common in some kinds of sedimentary rocks than others. There are many factors that can contribute to the likelihood of an organism being preserved as a fossil. Fossils are most common in limestones. That is because most limestones consist partly or mostly of the shells of organisms.

Detailed explanation-3: -Reason for sedimentary rocks to be the only rock type to contain fossils: The dead plants and animals, where they are buried by more sediment results in the accumulation of minerals from water in bones which leads to formation of fossils. This makes sedimentary rocks the only rock type to contain fossils.

Detailed explanation-4: -Sedimentary rocks are formed from deposits of pre-existing rocks or pieces of once-living organism that accumulate on the Earth’s surface. If sediment is buried deeply, it becomes compacted and cemented, forming sedimentary rock.