if fossils of an aquatic animal or plant are found in a place then that place used to be covered by water in the past & a fish is a kind of aquatic animal ->  if fossils of fish are found in a place then that place used to be covered by water in the past  if fossils of fish are found in a place then that place used to be covered by water in the past & fossils of fish are found on the land & a land is a kind of place -> the land used to be covered by water in the past