[living organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Superkingdom Prokaryota
     Kingdom Bacteria Cavalier-Smith 2002 - bacteria see Domain Bacteria Woese et al. 1990
       Subkingdom Posibacteria Cavalier-Smith 1987 see Domain Bacteria Woese et al. 1990
         Phylum Firmicutes corrig. Gibbons and Murray 1978 (Approved Lists 1980)
           Class Clostridia Rainey 2010
             1 Order Clostridiales Prévot 1953 (Approved Lists 1980)
             2 Order Halanaerobiales corrig. Rainey and Zhilina 1995
             3 Order Natranaerobiales Mesbah et al. 2007
             4 Order Thermoanaerobacterales Wiegel 2010