Which of the following organisms would you expect to find in a layer of rock at the bottom of a deep canyon? a) an ammonite b) a trilobite c) a dinosaur footprint d) a human skull

A trilobite. Trilobites became extinct about 250 million years ago while a ammonite became extinct around the same time as dinosaurs (65 million years ago). You wouldn't find a human skull or a dinosaur footprint