I don't know if anyone of you has ever heared of it before ...
I just came across this interesting little fact while reading a book about wolves and since they are named the same ...
It seems that the Dire Wolf
(Canis dirus) became distinct about 10 000 years ago, alsong wit a lot of other large animals of that time like eg. mammoths. The oldest bones that were found untill today are about 800 000 years old.
The Dire Wolf was larger than the 'normal' wolf, had shorter legs, a smaller brain and was according to several sources not that fast a runner.
But he had larger theeth.
Well, it is probably just a coincidence that GRRM named his wolves dire wolves.
Here is the wikipedia article on them.