 Gene mapping demonstrates that red foxes in North America have been isolated from their Old World counterparts for over 400,000 years, thus raising the possibility that speciation has occurred, and that the previous binomial name of "Vulpes fulva" may be valid.In the far north, red fox fossils have been found in Sangamonian Stage deposits in the Fairbanks District and Medicine Hat.Fossils dating from the Wisconsinan are present in 25 sites in Arkansas, California, Colorado, Idaho, Missouri, New Mexico, Tennessee, Texas, Virginia, and Wyoming.