There are several models of the Branching order of bacterial phyla, one of these was proposed in 1987 paper by Carl Woese. The branching order proposed by Carl Woese was based on molecular phylogeny, which was considered revolutionary as all preceding models were based on discussions of morphology. (v. Monera). Several models have been proposed since and no consensus is reached at present as to the branching order of the major bacterial lineages. The gene used was the 16S ribosomal DNA.