Here's what we know:
* Dogs are directly descended from wolves. Through selective breeding, wolves were domesticated and eventually became the dogs we know today.
* Foxes and dogs share a common ancestor. This ancestor lived millions of years ago and both groups evolved independently from that point on.
* Foxes are not a direct ancestor of dogs.
So, while foxes and dogs are related, they have distinct evolutionary lineages. Dogs did not evolve from foxes.