a shark is a kind of fish & a fish is a kind of aquatic animal ->  a shark is a kind of aquatic animal  a shark is a kind of aquatic animal & 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 ->  if fossils of sharks are found in a place then that place used to be covered by water in the past  if fossils of sharks are found in a place then that place used to be covered by water in the past & sharks live in oceans & an ocean is a kind of body of water ->  if fossils of sharks are found in a place then that place used to be covered by oceans in the past  if fossils of sharks are found in a place then that place used to be covered by oceans in the past & fossils of sharks are found on top of a mountain & the top of a mountain is a kind of place -> the mountain used to be covered by oceans in the past