The origins of progressive metal can be traced back to progressive rock bands from the late 1960s and early to mid-1970s such as Yes, Pink Floyd, Emerson, Lake and Palmer, Jethro Tull, King Crimson, Genesis, Gentle Giant, Focus, Renaissance, The Alan Parsons Project, early Queen, Kansas, Atomic Rooster, Uriah Heep and Rush. The latter five also often blended metal elements into their music. However, progressive metal did not develop into a genre of its own until the mid-1980s. Bands such as Fates Warning, Queensrÿche and Dream Theater took elements of these progressive rock groups – primarily the instrumentation and compositional structure of songs – and merged them with heavy metal styles associated with early Metallica, Megadeth and Iron Maiden. The result could be described as a progressive rock mentality with heavy metal sounds.