As far as I know the concept of readymades evolved from Dada ideas Dada ists used garbage newspaper clippings Objets Trouvees as material to make art The objet trouvee already contains the pop idea of using everyday materials like newspapers instead of more classical materials like paint and canvas Duchamp added to this concept by using readymades he also gave the idea a theoretical context Warhol added to this development by using readymade concepts He took a well known concept not necessarily its material representative and made it the subject of his works I would say that Warhol used ideas and images in a similar way that Duchamp used objects In other words Warhol or Duchamp may or may not be credited with something but their pointing and calling it art is part of a development that didn t start or stop with their work Art historians tend to talk about readymades as belonging to Duchamp Warhol is credited for incorporating popular ideas and methods into art