The answer has to do with continental drift. Three hundred and seventy-five million years ago in the Devonian, the world did not look anything like it does today. First of all, the climate was much warmer overall, so the north and south pole were not covered in ice. Secondly, the continents were not arranged in the same way as they are today. The continent Tiktaalik lived on was not located at 78° N. Instead, it was located almost entirely in the southern hemisphere. And the stream Tiktaalik probably lived in was located in the Northern part of that continent, very close to the Equator.