The line that people refer to now as Roadkill, was just called KB, Kine Bud, Skunk, Green Bud, etc until the forums used the term roadkill to describe the flavor.
This line was bred for commercial interests south of the boarder in the late late 70's / early 80's. It was meant to allow organized Mexican growers to achieve multiple crops per year without building massive light deprivation greenhouses at a time where it wouldn't be possible. So, how would this be possible? Ruderalis genetics.
That is the missing link that no one has pinned as one of the main contributors to the skunk aroma. Mexican x Ruderalis, possibly with some middle eastern genetics (Pakistani, Afghani, etc) then stabilized a few generation until the autoflower/photosensitive trait was locked into the line.
These grows were funded and set up with the help of American counterparts, that then used the network already established by the motorcycle clubs forming across the United States to move the product. Those motorcycle groups and many other clandestine opportunists started bagseed of that skunk line, growing them outdoors across the US. In Northern California, in the Midwest (Ohio, Michigan, Indiana), the South (West VA, North Carolina, Tennessee, Kentucky) and the Northeast (Mass, Maine, Vermont) etc. Many at the time didn't realize the plants were autoflowering because they were growing them outside. That was well before people were keeping mother plants indoors. Most started seeds, grew them out, and that was that. Those that did grow them inside quickly realized they were sexually unstable and would try to auto when rootbound.
The skunk isn't around anymore because it was an autoflowering, production based seed line. It is still in Mexican bagseed, deeply buried because those same groups continued to cross in Dutch genetics into the skunky seed line as time went on, to increase production and to dull the bouquet, as the skunk aroma had become synonymous with cannabis.