The Genealogy of Dylan's "Don't Think Twice"

With all the recent kerfuffles about the "blurred lines" of plagiarism, I was interested to note that Dylan was sued for basing "Don't Think Twice" on a 1959 release by Paul Clayton, "Who's Gonna Buy You Ribbons (When I'm Gone). Dylan got out of the suit by showing that Clayton had based his song on an old Negro public domain song called "Who gon Bring You Chickens"

There's an entire academic lecture about that song right HERE (you can skip across the first 10 minutes of introductions)

When I heard those clips of Marvin Gaye's tune compared with "Blurred Lines" on the news my first thought was that the 7 million dollars should go to the Gaye's drummer because that groove is what they copied...but how you gonna copyright a groove? The lawyers must be loving this.