Since a dinosaur cannot swim, explain how a fossil can be found on all continents

At one point in the early history of the earth, all the continents where merged together as a mega continent called "Pangea". so there actually was no ocean between the land, allowing for dinosaurs to roam freely across the entire land mass. when the land masses split up, the fossils went with them :)

Geologists use  seismic waves to  locate an earthquake's epicenter..