if fossils of a water animal or plant are found in a place then that place used to be covered by water in the past & ocean animals are a kind of water animals living in oceans & an ocean is a kind of body of water ->  if fossils of ocean animals are found in a place then that place used to be covered in ocean in the past  if fossils of ocean animals are found in a place then that place used to be covered in ocean in the past & fossils of ocean animals were found at the grand canyon & the grand canyon is a kind of place -> the grand canyon used to be covered by oceans in the past