Answer to Question 1
Early views were far-fetched ideas about rafting, land bridges, and island stepping-stones to get from one continent, across an ocean, and onto another continent.
Answer to Question 2
Mesosaurus was a freshwater reptile, and migration between the continents as they are now would have been impossible; however, if they were connected (as in Pangea), then this animal could have easily moved between the two by freshwater river systems.