procaryotes
   Domain Archaea Woese et al. 1990
     Phylum Crenarchaeota Garrity and Holt 2001
       Class Thermoprotei Reysenbach 2001 see Class Thermoprotei Reysenbach 2002
         Order Thermoproteales Zillig and Stetter 1982
           1 Family Thermoproteaceae Zillig and Stetter 1982
           2 Family Thermofilaceae Burggraf et al. 1997