Nice find. I guess everyone performs plagerism to their own extent. You can see a lot of Wolverton in Crumb for sure. Back in the 60's and 70's there was an artist in Ca I think by the name of rat or something. He did a long series of wolverton/crumb car characters like rat fink and such.
Now I have to go find some of those guys books. It's not a coincidence that most of the cartoonist are also well accomplished artists as well.
I never could stomach Picasso and his flounder people, but he was a real great realist as well.