Side one of the original LP is occupied by the 21-minute title epic track, beating both Genesis' "Supper's Ready" and Yes' "Close to the Edge" by a year.
Source: http://www.allmusic.com/album/tarkus-mw0000652026
I am not sure what exactly "beating … by a year" means in the context. Does it mean that "the title epic track" is better than the two mentioned LPs that were released one year later after Tarkus.