Eduardo Navas’ updated Regressive and Reflexive Mashups in Sampling Culture provides a sprawling (in a good way) map of remix theory and practice.
The megamix has its roots in the sampling practice of disco and hip hop. While disco in large part experimented with the Extended Remix, hip hop experimented with the Selective and Reflexive Remixes. Grandmaster Flash may be credited with having experimented in 1981 with an early form of the megamix when he recorded “The Adventures of Grandmaster Flash on the Wheels of Steel,” which is essentially an extended mix performed on a set of turntables with the help of music studio production. The recording included songs by The Sugarhill Gang, The Furious Five, Queen, Blondie and Chic.
[via Remix Theory]