Homo antecessor is an extinct human species dating from 1.2 million to 800,000 years ago , that was discovered by Eudald Carbonell , Juan Luis Arsuaga and J. M. BermÃ dez de Castro . Homo antecessor is an extinct human species ( or subspecies ) dating from 1.2 million to 800,000 years ago , that was discovered by Eudald Carbonell , Juan Luis Arsuaga and J. M. BermÃ dez de Castro .