They can conclude that the certain animal ( of the fossil) had either migrated to that place or was brought to that certain place this is also proof of of the Continental Drift Theory that there was a Pangaea and split apart around a certain time.
This could happen due to the split of the Earth millions of years ago. The Continental drift theory states that the Earth's continents have moved over geologic time relative to each other. Then, animals who were together at some time were separated by the continents drift.
