We can't know for sure what was the same kind because we weren't there. However, since dogs and foxes are so closely related, it stands to reason they are the same kind.
Evolution claims many very small, genetic mutations occurred over a vast amount of time. The mutations that aided in survival, which is determined by the environment, allowed certain mutations to flourish and others to die off.
Information is genetic.
I'm not saying evolution requires a change in kinds. What I'm saying is evolution claims all live came from one single cell. This cell evolved into bananas and bats and whales. That kind of evolution is not possible.
The evolution of two sexually compatible species breeding and producing something new is fully within creation, and also not new. Just a different portrayal of what was already there.
Natural selection, where one species develops a new coat color or longer beak, is also within creation. The information was already present, and the individuals with that characteristic were better adapted to the area, and survived.
The point where creation theory and evolution theory disagree is evolution by mutation into every living organism on earth. There is no evidence, and whatever evidence presented for evolution is usually right in line with creation.
http://www.darwins-theory-of-evolution.com/