It's pretty obvious that coyotes are members of the dog family, Canidae. In fact, coyotes, dogs and wolves all belong to the same genus - Canis. Genus is the closest relationship above the species level. The coyote, Canis latrans, the gray wolf, Canis lupus and red wolf, Canis niger and the domestic dog, Canis familiaris are related closely enough that they can interbreed. Rather than evolving from each other, it is likely these modern species evolved from common ancestors.
Foxes are more distant cousins of coyotes.
The gray fox alone belongs to the genus Urocyon. The fossil record indicates that North America, particularly its open prairies, was the setting for the evolution and dispersal of the canid family. Modern man, Homo sapiens entered the picture perhaps 100,000 to 250,000 years ago.