premise: if something that contains a thing is changed into something else that doesn't contain that thing, then that thing is lost / destroyed when that something changes into that something else sent2: metamorphic rocks do not contain fossils sent3: nearly all fossils are found in sedimentary rock sent4: if something is found in something else then that something else contains that something sent5: sedimentary is a class of rock sent6: metamorphic is a class of rock sent7: formation in the rock cycle means an old class of rocks changes into a new class of rocks sent8: if fossils are destroyed in rock transition , then there will be gaps in the fossil record.
hypothesis: sedimentary rock changing to metamorphic rock causes gaps in the fossil record