Most of us know that Antarctica used to be home to plants and dinosaurs and such. And we know the continents have shifted around a lot.
But the obvious explanation for Antarctic fossils, that Antarctica used to be closer to the equator, is wrong. When Antarctica had some temperate ecologies (presumably coastal ecologies) it was pretty much where it is today.
But the other continents were in different places and their shapes led to gulf-stream type effects, cycling warm water down from the equator.
(The same reason western Scotland is far more temperate than its latitude would suggest.)
As the continents drifted around a heat-pump made Antartica warmer and when they shifted some more that pump shut down and Antarctica became what we expect a polar region to be.
I was reminded of this reading this article. Yes, changing ocean currents can make an incredible difference:
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=389x7799942